Original subtitles

This is Gordon Welchman, a World War II codebreaking hero.

Without him, the top-secret German Enigma codes

might never have been broken.

The war could have lasted two more years

and tens of thousands more would have died.

Gordon Welchman should be famous.

His contribution to the war was as great as Alan Turing's.

Why have we never heard of him?

When I was a child, there was always, in the family, the sense

that Dad had done something quite important during the war,

but, of course, we didn't really know the details

and it couldn't really be talked about.

Gordon Welchman was the architect of a codebreaking technique

that was so clever and so powerful

that its wartime use at Bletchley Park still remains classified.

Like Turing, his extraordinary legacy began at Bletchley

and continues to this day.

Just as Turing is now celebrated as the genius behind the computers

that dominate our world, so Welchman's influence

is everywhere...but until now, it has remained in the shadows.

His secret work in code-breaking and communications

had an impact beyond anything he could ever have imagined.

Only now, with Edward Snowden's recent revelations

of the extent of global surveillance by GCHQ in Britain and the NSA

in America, can we understand Gordon Welchman's true legacy.

It seems to me that...

some of the things really have been kept secret too long.

Turing was undone by his private life, but is now

officially pardoned and celebrated as a genuine British hero.

But when Gordon Welchman chose to come out of the shadows

to reveal his secrets, the dark world of espionage was waiting.

This man, who dared tangle with his own legacy,

was ultimately destroyed by it.

September 1939.

As Britain declared war on Nazi Germany,

an extraordinary rag-tag army was being assembled

at Bletchley Park in Buckinghamshire to fight a secret war.

Their mission was to crack the hardest code ever devised,

created on a machine called Enigma.

Enigma lay at the heart of the German armed forces'

communications system.

If they could break in, these chess masters, crossword addicts

and bridge fanatics might just save Britain from the Nazis.

The best and the brightest were being recruited

from Britain's top universities.

Two of this elite were the renowned mathematician Alan Turing,

and the Dean of Sidney Sussex College, Cambridge, Gordon Welchman.

Gordon Welchman was actually quite glamorous.

He was good looking and he knew he was good looking.

He had a way with the ladies.

He was fantastically bright,

very pugnacious, obviously a very proud man.

He did mountain climbing,

he did sailing, he loved dancing.

Here was a man who had clearly been watching Hollywood movies.

He was kind of Errol Flynn and Robert Donat.

It's very much that kind of dashing young chap kind of feel to him,

as opposed to the shambling absent- mindedness of many of his colleagues.

Welchman was one of the five original elite codebreakers,

given the impossible task of decoding the Enigma Machine.

Enigma used a combination of rotors, plug boards

and wires to put the German messages into secret code.

The chances of breaking this code

were one in 159 million million million.

Welchman was set on a radical approach.

He ignored the unreadable messages,

and concentrated instead on what he could read.

The first few letters and numbers of each message were not in code.

These were call signs,

like addresses identifying who the messages were to and from.

It was a brilliantly simple starting point,

yet it would prove crucial.

As I studied that first collection, I began to see, somewhat dimly,

that I was involved in something very different.

Welchman started to track these call signs - who was communicating

with whom, how often, and in which direction.

They call it chat that comes over the air...

..and by this means we can build up

a picture of a German unit

of the air force, for example,

the headquarters, any out stations it has,

and how they keep in touch with each other and send messages.

We were dealing with an entire communications system

that would serve the needs of the German forces.

The call signs came alive as representing those forces

whose commanders would have to send messages to each other.

The technique Welchman was using was called traffic analysis.

It was this simple observation, that a message must include

details of the sender and the receiver,

which would allow Welchman to see the entire network of the enemy.

With this simple insight, modern codebreaking was born.

And it allowed Welchman to begin unravelling the enemy's secrets

from hundreds of miles away.

And they had a big wall map and you could, visually,

see the whole set-up of the German communications system.

It was Bletchley's first major breakthrough.

And it had been achieved without reading a single message.

Without an analysis of traffic, you would never have been able

to use cryptography to win the war.

When you hear phrases like "traffic analysis" or "signals intelligence",

it doesn't immediately sound quite so glamorous, really.

I think possibly that's one of the reasons why Gordon Welchman

hasn't been recognised so much, but if people knew just how absolutely

he was the kind of the spine of the entire Bletchley Park operation,

then they would look at him in an completely new way.

The Enigma codes had still not been broken, but Welchman already

knew the exact position and strength of thousands of German troops

and hundreds of aircraft, using the power of traffic analysis.

He now realised that Bletchley Park could become as forceful

a part of Britain's defences as the Army, Navy and Air Force.

Their weapon would be intelligence.

No-one else seemed to be doing anything about this potential

gold mine, so I drew up a comprehensive plan,

which called for the close co-ordination of radio interception,

analysis of the intercepted traffic...

..breaking Enigma keys...

decoding messages on the broken keys,

and extracting intelligence from the decodes.

This was still the "phoney war",

before fighting between Germany and Britain had begun...

..but Welchman was proposing a total reorganisation

of Bletchley Park, a radical plan that would require far more people

than a few tweedy professors solving puzzles.

Welchman went to his boss.

He won high-level approval for my plan

and we were able to start recruiting the high-quality staff

that would be needed.

Welchman's creation was called Hut 6,

a modest name that belied the magnitude

of just what was achieved within its walls.

In this modest hut, brilliant people made breakthroughs

that helped change the course of the war.

For more than 70 years, it lay derelict, unloved and abandoned,

until it was painstakingly restored by the Bletchley Park Trust

to how it would have been in 1940.

We had two or three or four little lights

hanging on wires from the ceiling, and we had collapsible chairs

and tables - not very comfortable -

and that was our equipment,

so it really wasn't for a high-powered government machine.

Jane Fawcett was one of 400 people who worked at Hut 6.

All were sworn to the utmost secrecy.

Many took their secrets to their graves.

Now, only a handful are still alive.

I was in the Royal Corps of Signals

before, rather against my will, I was transferred to Bletchley

and there I was learning to be an interceptor.

I saw a notice - "Men with suitable qualifications

"required for transfer to the intelligence corps".

I was a bit of a romantic and I thought, "Well, you know,

"I might get involved in some clandestine operations."

Bletchley scoured the country

for the right sort of people for top-secret work.

You have the very posh debutantes...

..drawn from the higher echelons of society, initially,

apparently, because it was felt

that the smarter a girl's family,

the more likely it was that she'd be able to keep a secret.

Happy days.

I did the season, which was where the debutante photographs

come from, and I regarded that as a complete waste of time and money.

And then the war broke out.

I got a letter from one of my best friends, who said,

"We're terribly busy. We really need you. Could you come and help?"

As German Panzers raced across Western Europe, Bletchley Park

at last found a way to read Enigma traffic.

The intelligence it produced was codenamed Ultra.

Almost immediately, it gave them a major breakthrough.

30 years after the war, in the only filmed interview Welchman

ever gave, he revealed how this intelligence had been turned to

advantage during the British Forces' retreat from France at Dunkirk.

In the battle of France, probably the most important thing

which came out of Ultra, we were still breaking it in,

was that it was realised so early

that we were in a hopeless position.

It showed Hut 6 had been established just in time.

And it was decided to get out as quick as we could.

And this meant that there was time to organise the armada

of small boats that managed to get the troops back out from Dunkirk.

The immediate success of Hut 6

was a testament to Welchman's steely-eyed vision.

You do need this because,

in an establishment filled with absent-minded boffins who were

sort of walking into cupboards thinking it's the way out of the

room or trying to stuff sandwiches into their pipes, you need someone

with, you know, the clarity of thought of Gordon Welchman.

Well, I think he was the right person at the right time.

I think he probably had a lot of personal characteristics that

were really vital for his work here.

He doesn't have any time for faffing about.

There's a war on and he has a very particular idea

of how this war should be fought.

By the end of 1940,

Hut 6 was at the heart of the whole Bletchley Park operation.

Here, they used traffic analysis to select

and target particular German radio networks and operators.

Their traffic was then intercepted

and decoded, thanks to a remarkable new mechanical device,

which was helping to break key Enigma signals, on a daily basis.

It was called the bombe.

It simulated all the possible rotor configurations

of the Enigma machine.

The bombe could check them hundreds of times faster than a human being.

But it was very limited. To run a test, known as a bombe run,

it needed to compare a short phrase from the code

with what the codebreakers guessed might be the original message.

For example, German messages might begin with the words "Heil Hitler".

This guessed text was known as a crib.

If they were right in their guess,

the bombe could start cracking the code.

But they needed accurate cribs.

To find them, Welchman realised the human routines of the German

operators could be the vulnerable link.

What Welchman discovered

was that by understanding the way that the Germans

used their communications, you could start to predict more easily

where particular types of message would come.

There was a German commander in Brittany somewhere

who. during the war, regularly sent in every morning a message, saying,

"Alles ist in Ordnung", "Everything is OK here".

It was the same phrase he used every morning,

which was a godsend to the decryptors in Hut 6.

It was a godsend because if they could work out what these

encoded letters were, they were on their way to cracking the code.

So cunningly, they targeted specific operators,

trying to provoke them into using predictable phrases.

They called it gardening.

This German officer in Brittany

used to report, "Lone aircraft approaching".

So we used to send regularly this aircraft over,

so he'd send the same message.

Armed with a crib, the Bletchley team could now start a bombe run,

and hope to find the Enigma settings.

But it was a race against time.

The German codes were changed at midnight...

..and the bombe might take days to find an answer.

Even if they cracked the code,

it would be too late to help the Allies.

Welchman's genius was to come up with a modification

of Alan Turing's brilliant design...

..and make it work many times faster.

It was Gordon Welchman

who spots the one thing that the machines

need that could give them

an almost uncanny elegance

and beauty in the way that they worked.

Welchman came up with an inspired, improvised solution.

A simple electrical circuit that dramatically improved

the chances of finding the correct rotor settings.

It was called the diagonal board. The impact was immediate.

It reduced bombe runs from days down to hours or even minutes.

The German codes could be cracked,

sometimes before they were even read by the intended enemy recipient.

So here we see an example of Gordon Welchman's fantastic mathematical

intelligence coming through, easily a match for that of Alan Turing.

At Dunkirk, Ultra intelligence had proved its worth, snatching

thousands of British troops from death or certain capture.

In May 1941, Bletchley Park proved intelligence...

could also bring victory.

The main part of our fleet was out pursuing the Bismarck.

She was the latest German ship

and the best thing they'd got in the navy and very important.

The battle cruiser Bismarck was the most feared ship of the German Navy.

On May 24th 1941, she sank the pride of the British Navy...

HMS Hood, Britain's most modern and biggest ship.

1,400 British sailors lost their lives.

Only three of her crew survived.

Churchill ordered the might of the Royal Navy to hunt Bismarck down.

But where was she?

At Bletchley, Welchman's team believed German messages

might reveal her location.

Gordon was always in the depths of the deepest thought,

so he wasn't a very sociable person, as far as I remember, but then

why should he be? Because he hadn't got time to talk to people like me.

He was just...

riding a tremendously important horse

and trying to get there quicker than it was possible to get there.

Sifting through the entirety of German naval communications

for any reference to the Bismarck was a daunting challenge.

What I had to do was to take the Enigma telegrams

as they arrived in Hut 6, and I had to put them into the machine.

Then I had to look at them and see whether - they were all

in German, of course - see whether they appeared to be of any interest.

Then, the breakthrough they had been waiting for.

We discovered this message from a German commander

to the commander of the Bismarck saying, "Where are you going?

"I'm worried about my son, who's on board".

And the message came back, which I got, which said, "Brest."

At last, they had a location.

The Bismarck was heading for the port of Brest

in Northern France, being used by the German Navy.

A powerful Royal Navy battle group

was immediately ordered to hunt down the Bismarck.

NEWSREEL: In this, perhaps the most dramatic naval film ever taken,

you'll see salvos from the Bismarck

failing to hit one of our battleships.

This was during the chase right across the Atlantic,

when the Nazi ship was running from the guns of our squadron.

And I was on duty for 24 hours during that period

without really having anything to eat or certainly no sleep.

But it was terribly exciting.

A torpedo dropped from a Swordfish biplane

disabled the rudder of the Bismarck.

The British cruisers closed in.

We were all absolutely on our toes wondering what was going to come

through next because we knew it was one of the major battles of the War.

When these pictures were taken during the action,

the Bismarck was nearing her end.

It fell to Hut 6 to decode the very last message sent from the Bismarck.

"Ship unmanageable. We shall fight to the last shell.

"Long live the Fuhrer."

And eventually they sank her.

The flagship of the German Navy went down with over 2,000 of her crew.

I mean, that was a day to remember.

We were...constructing a jigsaw but half the pieces were missing.

Now it all made a picture and the whole jigsaw came together.

We were invigorated immediately.

It was Britain's first significant victory

in the darkest days of World War II.

Bletchley Park had proved that intelligence could sink ships.

Yet Welchman knew that they were chronically under-resourced,

still a cottage industry and they could achieve so much more.

The staff and the bombes were working around the clock,

but vital intelligence was not being picked up in time.

Welchman realised that he had no choice but to go to the very top.

He, together with Alan Turing and Stuart Milner-Barry, wrote

this fantastically audacious, rather cheeky message to Winston Churchill.

Gordon put a lot of pressure on Churchill to produce more staff

for us because he realised that we were grossly over-worked

and under considerable strain and that our equipment was appalling.

Now, imagine writing a letter like this to Winston Churchill.

"Dear Prime Minister,

"some weeks ago you paid us the honour of a visit

"and we believe that you regard our work as important.

"We think, however, that you ought to know that this work is being held up,

"and in some cases is not being done at all,

"principally because we cannot get sufficient staff to deal with it."

This has got Gordon Welchman all over it. Just go direct to the top man.

And that's exactly what Gordon Welchman did

and he got an instant reply.

"Make sure they have all they want on extreme priority

"and report to me that this has been done. Action this day."

This memo had a remarkable effect.

Bletchley did indeed receive more resources.

Major building work followed.

The park was transformed from a ramshackle collection of huts

into a giant code-breaking production line.

Now, 70 years later, this is what remains of it.

Hut 6 moved from their draughty wooden shed

into this huge brick building.

Thousands of people worked here around the clock

and in conditions of absolute secrecy,

breaking into supposedly unbreakable German messages.

It represented a remarkable recognition

of the power of codebreaking in the war effort.

Two bombes became 200.

The population of Bletchley Park steadily rose

to over 8,000 people by the end of the war.

And this was Welchman's office.

His vision had turned a country mansion into the world's

first code-breaking factory.

Bletchley Park was breaking Enigma daily,

revealing the inner secrets of the German war machine.

And it was changing the course of the war.

They tapped into Rommel's battle plans,

and his forces were driven out of North Africa.

They located the U-Boat wolf packs lurking in the Atlantic,

and these were ruthlessly hunted down.

And, thanks to Bletchley,

the allies knew they had successfully deceived Hitler

into believing the D-Day landings were purely a diversion, leaving his

forces exposed to the mass invasion of Allied troops that followed.

The boffins at Bletchley were taking on the might

of an awe-inspiring Teutonic army and winning.

Their work has been credited with helping shorten the war by two years

and Gordon Welchman was central to this achievement.

To think of him as the Henry Ford of cryptography is not a bad metaphor.

It's the industrialisation of cryptography.

That's an astonishing achievement.

So this is Hut 6. How exciting. This is the place.

The decoding room.

Ah, look at these machines.

So this is administration.

Ah, this is Dad and Stuart Milner-Barry in this office.

And I can see who's who.

There's Dad's pipe. Many memories of him fiddling with pipes.

There must have been haze of smoke.

They've done a beautiful job and, look, "Stronger every day,

"we've got to keep at it."

They must have needed that a lot during their 15-hour days.

My goodness, Dad actually sat here.

When you know how it went

from just 100 or 200 people

arriving in August 1939 at Bletchley Park to, you know,

nearly 10,000 people working there in January 1945...

If we pick him out as probably the most central figure,

his legacy is in what Bletchley Park achieved, what Bletchley Park

contributed to the success and the Allied victory in 1945.

It's hard to have a bigger legacy than that.

One war was over, but another was about to start.

It was to see another remarkable

contribution from Gordon Welchman, but at a devastating personal cost.

Operations at Bletchley were finally shut down in the spring of 1946.

And most of the people who had worked there were allowed to leave

and rejoin everyday life in post-war Britain.

But they were given dire warnings

never to speak of their wartime work.

The amazing thing about Bletchley, to most of us who survived it,

was the fact that we did manage to keep it secret.

I'd never been allowed to talk to anybody

about what I'd been doing at Bletchley.

My mother and father didn't know. My wife didn't know when I married her.

I mean, unbelievable really, that such secrecy should have prevailed.

Knowing that you've done so much to help change the course of events,

how do you adjust to a life afterwards?

However, the legacy of Hut 6 would endure.

Welchman's creation would find itself the model for GCHQ

in Britain and the National Security Agency, the NSA, in America.

But the British Government, almost bankrupt from the war,

was forced to scale back their operations.

He found himself more and more frustrated with the attitude

of the British government towards this new field

that they'd help create, which is of course this kind of study

and development of communication systems and of electronics.

It was such a terrible waste to him.

Bletchley had led the world with its remarkable inventions,

but Welchman now thought Britain was squandering this legacy.

You also have a sense of a man who understands very, very well about the

computer revolution, the computer age about to come into being, because

this is a computer age that is brought into being at Bletchley Park.

Welchman realised he had to seize the opportunity

to build on what he'd already created at Bletchley Park.

He was determined to stay at the forefront

of the computer revolution.

That meant America.

NEWSREEL: The Massachusetts Institute of Technology was asked

by the three military services to establish a new research centre.

They created MITRE to develop top-secret defence technologies.

And they were recruiting the finest brains.

I imagine that the powers that be in England

got in touch with the powers that be in the United States

and said they had this wonderful guy and he would like a job.

Working here put Gordon Welchman

right back at the heart of another intelligence war. The Cold War.

NEWSREEL: One of the most dangerous threats to our nation's security

is the possibility of attack by high-speed enemy bombers

armed with nuclear weapons.

This was warfare on a global scale.

Huge strides in technology were needed

to hold the so-called Red Menace at bay.

During that period was the Cuban missile crisis - OK,

I mean, that was really a tough period, OK?

I built a bomb shelter in my basement in Bedford, Massachusetts.

A large-scale nuclear attack on the United States could produce

a patchwork pattern of fallout covering two-thirds of the nation.

We cannot afford to take that chance.

Welchman was given the highest civilian security clearance,

but it meant becoming a US citizen.

The job did require a very high security clearance.

In fact it was high enough

so that the fact that I had it was classified.

With the frightening prospect of a nuclear confrontation,

Welchman was given the vital task of

ensuring US military communications were capable of withstanding attack.

All he had learned at Bletchley Park was now applied to help

achieve American supremacy, on a scale that would dwarf Hut 6.

Traffic analysis in World War II

led Welchman to understand the way

information flowed in battle and how many different ways it flowed.

Welchman realised military communications

hadn't really moved on since his days at Bletchley.

Headquarters issued an order, units made reports.

But in modern warfare,

instant access to battlefield information was essential.

Repeat, this is a yellow alert.

And computer technology was advancing fast enough

to make this possible.

He said, "Hey, with this digital communications,

"we can do some things that we've never been able to do before".

Where once he had used traffic analysis to break into German

networks, now Welchman used all his experience to do the opposite.

He developed a new kind of network - constantly updated,

immediately shared and totally secure,

to serve a battlefield where information was power.

Everybody periodically broadcast bits of information

about where they were, what they were doing.

Welchman called his idea a horseshoe,

but we would all recognise it today as the cloud.

Welchman's system instantly connected planes, submarines,

ground forces, battleships -

all the elements of the command structure all at the same time.

And that went out into the sky

and anybody who was interested in knowing what friendly aircraft

are in this area could immediately get those reports - sort of

like an instant Google and this was three, four decades before Google.

Gordon came up with this radical idea and people looked at it

and said, "Hey, that's pretty good."

And so, you know, my boss called me in and said, "OK, make it work".

His ideas were really a game changer.

They changed the way people thought about command and control

and they changed the way battles were managed and warfare was fought.

It's still in use today and it will be for a long time.

The legacy of the two giants of Bletchley Park

endures to the present day.

Alan Turing made a decisive contribution

to the computer revolution.

Gordon Welchman's work prefigured

how the internet and the cloud would later develop,

and how technology would enable a surveillance society.

In 1971, Gordon Welchman moved to the New England town of Newburyport

and married his third wife, Teeny.

We started coming pretty much as soon as he moved in,

and we visited regularly.

It was a place he really enjoyed.

He liked living here. He loved the town.

He was now 65 and still at the peak of his powers.

He had made a decisive impact on both the Second World War

and now the Cold War.

Yet everything he had achieved

was known only within his clandestine world.

Remarkably, the success of Bletchley Park

had stayed secret for two decades.

But then, in 1974, an event occurred which had unexpectedly

far-reaching consequences.

The Ultra Secret, a book by an ex-MI6 Officer,

revealed for the first time the role of codebreaking

in winning the Second World War.

Whitehall agreed that it would be better

for there to be a controlled disclosure,

a non-sensational version, by Fred Winterbotham.

But that opened the floodgates.

Suddenly daylight was being shone on a hitherto secret world.

It was a shocking moment for all those, like Welchman,

who had taken their oath of secrecy so seriously.

For years and years I didn't even read the histories of the war

because I was afraid that somehow or other I might reveal

some things I'd learnt from Ultra.

Nevertheless, Welchman now felt, for the first time,

he could tell his family what he had done in the war.

I think it was an enormous relief.

He could tell these stories, and could talk to us,

and could share memories that he'd kept tamped down for so long.

There was a transformation in his manner.

I think another thing that was a revelation was the discovery

that my grandfather, of all people,

was a sort of prototype of a computer geek.

By chance, another veteran of the secret war

was also living in Newburyport.

I was invited to a dinner party one night. Right there.

And then, out of a blue sky, Gordon said,

"Well, I was at Bletchley during the War."

And, of course, my mouth just fell open,

because I had been working as an intercept operator at Chicksands.

All the stuff that we had taken went to Bletchley.

An idea began to form in Welchman's mind that he should write his story.

I seem to have a very special responsibility,

in that I was the only person alive with inside knowledge

of a very telling episode in cryptologic history.

In 1977, he also took the deliberate decision to appear on the BBC,

which, for the first time on television,

dared to reveal the still-classified story of Ultra intelligence.

I don't know whether I should say this.

But it seems to me that...

..some of the things really have been kept secret too long.

That there is a point at which...

..you do more damage by deceiving your own people

about the true history of World War II than you could possibly do

by telling now the story as it actually happened.

He wrote his book here.

He would go off on his own if he wanted to work,

and you didn't disturb him, yes, in his study or his office.

But then he'd emerge, and he'd be Grandad again.

Determined to set the record straight,

as well as to give public recognition to those whose work

had been war-winning, he discreetly contacted old colleagues.

He wrote from his own prodigious memory.

He had no access to official papers, which were still classified.

It would take him seven years.

I think it was almost a compulsion to write the book.

It's a very kind of human and understandable thing

for this man to think, "I don't care how much trouble this gets me into,

"I want the world to know what I achieved".

I think my father felt that he had a very important insight

on a particular piece of history which very few other people had,

and he just kept reading the obituaries

and realising that there were fewer and fewer people left.

The Hut Six Story was published in the United States in February 1982

and in the UK the following May.

For the first time in print,

the full secret history of codebreaking's role in World War II

was laid bare, including Welchman's use of traffic analysis.

As well as telling the true history from an insider's perspective,

the book included a warning.

Welchman believed lessons from the war were being ignored.

The Americans were making the very same mistakes

with their security that the Germans had once made.

He thought he could talk about this in a way

that would reach the general public, that would not disclose any secrets,

it would not tell tales you shouldn't.

He hoped it would make some money,

but he really hoped it would generate a conversation.

The secret world didn't wait long to hit back.

I was on my way to work and this car speeded up

and stopped right smack in the, almost in the middle of the road.

Nobody stops there so I had to see what was going on.

There's Gordon's house, right there, and then two men jumped out,

wearing black suit, black tie and black sunglasses.

They looked like the Men In Black. And they raced across the street.

Gordon answered the door and you could see them, you know,

busily discussing something and, all of a sudden, Gordon took the door

and he slammed it, almost in their faces.

Later, I found out that it was the National Security Agency.

There had been books about "the Ultra secret"

prior to his publication.

There was no putting the toothpaste back in the tube.

The secret was out, but Welchman's book was

the first about cryptanalysis by an actual insider who had done it.

What Gordon Welchman was doing was not so much disclosing

the nuts and bolts of attacking Enigma.

He was saying there is no communication system

that can resist this kind of cryptanalytical attack.

NEWSREEL: If our continent were attacked,

this red telephone would be lifted from its cradle and instantly

the United States would launch the greatest counterattack in history.

Signals intelligence remained, at that time,

at the very heart of the intelligence conflict

that was being conducted during the Cold War.

So this was as important and as secret as it could get.

I think that people who saw what he wrote

felt he was imperilling current operations.

Welchman's World War II work in traffic analysis might have

been 40 years before, but what he had discovered was still so vital to

the secret world, that revealing it, even now, was considered dangerous.

It was an irony that would all but destroy him.

On the 22nd February 1982, the NSA returned.

These two young gentlemen came in,

one from NSA and one from,

I believe it was Air Force intelligence.

And they said, "This information has never been declassified,

"and therefore is still in violation of the wartime secrets laws."

Gordon was taken aback. He said, "This is absurd."

They were delivering a message to him, and it was an ominous message.

I believe they had conversations with Mr Welchman.

Beyond that, I'm not sure that I can talk about anything meaningful.

It became clear the American authorities

were not going to back off.

It was really quite devastating.

He was quite unprepared for that.

Welchman knew about another writer who was preparing a book

revealing the dark secrets of the NSA itself,

which was doing everything it could to stop publication.

Welchman enlisted his help.

We lived in the same area,

so we could actually get together physically

and it was the kind of things that you don't want to

talk over the telephone, especially when you're dealing with NSA.

They were basically telling him he couldn't write anything.

He couldn't do any publicity,

he couldn't answer questions from reporters, he couldn't appear

on television shows and so forth and that was a really big problem.

The NSA was effectively trying to kill Welchman's book.

Threatened with jail, he was forced to cancel all publicity.

Publication in the UK made matters worse.

Then-Prime-Minister Margaret Thatcher had to be briefed

on the problem of Gordon Welchman.

The Cabinet Secretary wrote to the Prime Minister explaining

what issues were at stake, also explaining that it was unlikely

that there was any legal way of proceeding against Gordon Welchman.

Instead, Bamford believes the British pushed the NSA

to keep up the pressure on Welchman.

I think GCHQ played an enormously important role,

maybe the most important role. I think a lot of the guidance

that NSA was getting was coming from GCHQ.

The directors of NSA and GCHQ

were almost like partners in the same organisation.

The NSA threatened Welchman with a little-known law

drafted in 1940 to deal with the sharing of cryptology.

This same law is now being used on NSA whistle-blower Edward Snowden.

It's part of the Espionage Act.

I think it's ten years in prison and a heavy fine.

So these were very, very serious charges.

I could see he was nervous.

I could see the psychical effects that the NSA was having on him.

That devastates somebody that's spent their entire life trying to protect

US and British governments and now they're being told that they're going

to be charged with a crime possibly, of giving secrets to the enemy.

There was one final act with devastating consequences.

On the 29th April 1982, Welchman's security clearance was withdrawn.

All of a sudden, he disappeared.

"Dear Mr Welchman.

"As you know, the Department of Defense has raised questions

"about your recent publication.

"The MITRE Corporation believes it would be mutually beneficial

"to temporarily suspend your access to classified materials

"and technical data in the custody of MITRE,

"until the situation has been resolved.

"This suspension is effective this date.

"Please acknowledge receipt of this letter

"by signing in the space provided below."

And he signed below.

Yes, this would have been... absolutely devastating.

Rather than stay silent, Welchman went on the offensive.

He wrote letters and articles which he hoped would exonerate him,

including a recently discovered unpublished paper,

"Ultra Revisited: A Tale Of Two Contributors".

The stories of Alan Turing's life and mine have two things in common.

First, we were regarded by our boss as the two greatest contributors

to the wartime success of Bletchley Park.

Second, we have been branded as "security risks".

What has happened to me

can be compared with what happened to Turing.

For many in the intelligence community, Welchman was being naive

to imagine he could reveal the secrets of Hut 6 with impunity.

But he never lost his belief that this was information

the public needed to know.

I'm afraid there's a basic fact is that Gordon Welchman

who had not been involved in any of this after the war,

was in no position to know himself,

and was in no position of course to set himself up as the authority

on what could and could not be released.

What they didn't stop and think was that the way in which

cryptanalysts approached the breaking of Enigma was as sensitive

in the 1980s and is as sensitive today as it was at the time.

He was getting into an area of decision-making

that wasn't quite for him.

With Welchman gagged by the security services, his book flopped.

The remaining unsold copies of The Hut Six Story were pulped.

The strain was also coming at a very difficult time.

He'd had some more medical problems.

And to add to the pressure, Welchman's wife, Teeny,

believed they were being put under surveillance.

She did talk about, you know, the feeling of being watched.

It really did put a blight on the end of his life.

It was a cruel irony that Welchman, a master of the secret world,

who helped win World War II by breaking enemy codes

and helped the West win the Cold War

by keeping their communications secret,

would himself fall foul of the secret state.

I believe that the rules at the time about secrecy

were really inflexible.

The people who administered inflexible rules themselves

had spent a full career being indoctrinated

with the idea that secrecy was the base.

I am, today, glad that the book is out.

My hunch is it had more to do with the sort of pathological

and almost hysterical secrecy, which is a kind of British disease

and it may be that he was just a victim of that in its dying moments.

I'm not saying that he was blameless.

He had broken the procedures and the law was never invoked.

But he lost his job and his livelihood...

without ever appearing in court or ever facing any criminal charge.

By now, Welchman was seriously ill with cancer,

but he continued with his fight to set the record straight.

It prompted this letter from the head of GCHQ.

"It was, as I believe you know, a great shock to my predecessor

"and to the US authorities when you published your book in 1982,

"without consulting us and in defiance of undertakings

"which thousands of others have faithfully observed.

"I am disappointed to find you following a similar path

"again in 1985."

The letter went on, "It is a bitter blow to us,

"as well as a disastrous example to others,

"when valued ex-colleagues decide to let us down."

And, finally, you know, I think

he realised that it wasn't going to go away.

They probably couldn't successfully prosecute him,

but they would break him financially.

Gordon Welchman never redeemed himself.

Three months later, on October 8th 1985, he died.

It made two of the last three years of his life really quite hellish.

But his legacy would continue.

After his death, his methods

and insights not only became part of the West's military thinking,

they became the very heart of the new intelligence networks,

as the world became more and more connected, via computer.

In June 2013, Edward Snowden leaked tens of thousands

of highly classified files.

Our intelligence agencies were harvesting metadata -

our phone numbers, our computers' IP addresses,

the websites we visit, those we message or call

and where we are at any given moment.

It suddenly occurred to me that actually what we now do with metadata

is in a sense a highly-developed version

of what Welchman started with traffic analysis.

That's what it is. Metadata and analytics now, in a digital world,

are essentially our way of doing traffic analysis

and it can be very, very revealing.

For many, what Snowden was revealing

was that we live in a surveillance state,

that GCHQ and the NSA have turned Welchman's legacy

against their own citizens, destroying our privacy.

But, for others, traffic analysis is keeping us safe.

After 9/11, it was CIA analysts,

heirs in many ways to Welchman and Bletchley Park,

who led the hunt for the most wanted man on the planet, Osama Bin Laden.

If I want to understand how to destroy this terrorist

organisation, if I want to take them down as an organisation,

then I have to look for their vulnerabilities, and to look

for their vulnerabilities, I have to understand their network.

The technique they used had been pioneered by Gordon Welchman

in Hut 6. It was the modern equivalent of his traffic analysis.

What we call link analysis or network analysis - the more

sophisticated version of that - is the absolutely critical tool

in finding covert networks, whether it's terrorists or crime networks,

because they're trying to hide their entire organizational structure.

How can I find these people or this place? How can I do it

with enough precision that I'm not just going to bomb an entire town?

First developed at Bletchley Park and then honed in the States,

data analysis would now lead a team of US Navy Seals to Osama Bin Laden.

Today, Edward Snowden is branded a traitor

for revealing the secrets of modern traffic analysis.

Gordon Welchman also went public for something he truly believed in.

But after a glittering career,

he spent the last three years of his life fighting illness,

fighting for his reputation

and feeling outcast from the very world he had helped build.

Alan Turing's brilliant work at Bletchley Park has made him

an iconic figure in our history.

His pioneering spirit sparked the computer revolution

and is now part of all our lives.

It was Gordon Welchman's misfortune that his equally brilliantly

achievement has not earned him the public accolades it deserves.

His top-secret work impacts on every one of us now

as much as Turing's.

But it was to be this very secrecy that was to deny him

his rightful place in our history.

Gordon Welchman unquestionably was a genius.

His genius, however, is probably only recognised

within the intelligence community

to which he made such an extraordinary contribution.

99.9% of the people in the world

have never heard of Gordon Welchman and you say the name Gordon Welchman

and they just kind of stare back at you,

and yet he contributed so much.

Shortening the war by two years? Good heavens.

Saving thousands of lives and yet nobody knows who he is.

I have no qualms about saying he was a genius.

Of course a theme here

is "Gordon Welchman, forgotten man of Bletchley Park."

I'm enormously proud of my grandfather.

Still sometimes distressed about what happened

after he published his book and how much that meant to him.

He was certainly proud of what he'd done.

There's always an element that it was a pity he didn't get recognised

but it's too bad he couldn't be here today.