Original subtitles

On a spring morning in 1944, a glamorous young woman,

dressed to kill and wearing too much make-up,

cycled through the country lanes of southern England

on a mission from her German spymaster.

Her mission was to report on the build up of Allied forces

for the coming invasion of Europe - D-Day.

She was building a detailed picture

that, in the hands of the enemy,

could destroy the Allied chances of a successful assault on occupied France.

Her German spymaster was delighted with her reports,

congratulating her on her sterling work for the Third Reich.

In fact, this German spy was not what she seemed.

Every word she sent was false.

ENIGMA MACHINE BEEPS AND WHIRRS

Her lies were part of a web of espionage that drove

the biggest deception in military history...

and helped ensure Allied victory on the beaches of Normandy.

A complete web of military fiction was created.

There were events which never took place.

I went a few dozen times to meet the Germans.

I never felt absolutely certain that I shall come back.

He was really entering the lion's den.

He could've been betrayed at any time.

PLANE ENGINE DRONES

I think it was overwhelmingly exciting,

because you were playing with fire.

On the morning of June 6, 1944, 150,000 Allied troops

stormed the beaches of Normandy and broke into Nazi-occupied France.

Today, we think of D-Day as a great military victory.

But it was not just the heroic action of the brave soldiers that won the day.

Alongside the Allied troops that day, was another unseen force.

They fought not with guns, bombs and bullets,

but with subterfuge and stealth,

and a web of espionage spun from 1,000 little lies.

Five spies whose mission was to do nothing less than invade and control

the mind of the man at the very top of the Third Reich...

..Adolf Hitler.

Each of them had begun their careers working for the Germans,

but their stories would culminate in a tale of triumph and tragedy

that nobody would've believed at the time,

and barely seems believable now.

Throughout the war, Hitler believed he had a fully-functioning,

highly efficient network of spies reporting on the British war effort.

In fact, every one of those spies was acting as a double agent under British control.

Not some, not most, but ALL of them.

Since the breaking of the German Enigma code in 1940,

the British had been able to decipher German radio traffic.

And that included spy traffic.

Information that would allow them to know when and where every spy

sent by Hitler was due to arrive in Britain.

The penalty for spying was death.

But there was another option.

The majority of agents gave themselves up

or reported immediately, because they wanted to work for us.

And so it seemed sensible when we got an agent

to at least pretend that he was operating freely.

And this opened the possibility of using them for deception.

Those who chose to work against the Fuhrer now came under the control

of department B1A -

the division of MI5 responsible for running double agents.

The unit's presiding genius was Lt Col Thomas Argyll Robertson,

known to his friends by his initials - Tar.

His nickname was Passion Pants, on account of his tartan trousers and flirtatious manner.

He was a natural gambler with a ruthless streak

and an uncanny knack for seeing into darker corners of the human mind.

We were able to tell when an agent was coming over

and was being prepared to be sent to this country as a spy.

So that you could welcome him? So that we could welcome him,

which we did in no uncertain terms, I can assure you. We generally knew

when he was going to arrive and where he was going to arrive.

He was a lovely man. He was frightfully good-looking.

He sauntered into the office in his tartan trews,

and was always very friendly with everybody,

and had a great sparkle in his eye.

I don't think he was a scholar, particularly,

but I think he had the certain sort of special brain that was able to

see round corners and invent things

that would become believable if they were put across in a certain way.

Tar Robertson planned espionage with the top-secret Twenty, or double-cross, Committee.

Churchill himself had assembled this group of men who could see around corners,

because he knew that Hitler and his military tended to think in straight lines.

The Germans' ruthless efficiency

made them more vulnerable to deception.

They were so proud of the fact that they'd got these agents in this country.

Therefore, they're sort of more gullible.

The Twenty Committee now planned to gamble this pack of double agents on one great deception.

Even if this meant they could never be used again.

D-Day was that opportunity.

Hitler's war had become the bloodiest in history.

The Holocaust was a raging and millions were dying in Russia

and on the Eastern Front.

The Allied commanders knew that the war could only be won

by invading France and driving the Germans all the way back to Berlin.

But Hitler had constructed a zone of death to defend the coast,

the Atlantic Wall.

And his forces greatly outnumbered the Allies.

Churchill knew he couldn't win by brute strength alone.

Everyone knew the invasion was coming.

The vital question was where.

Hitler believed an attack would come in Calais,

the nearest French port to Britain.

And here, he massed a huge defensive force.

It was the obvious target

and therefore the British decided not to attack it.

Normandy was further away, but it had gently sloping beaches,

ideal for landing thousands of troops.

It was also less heavily defended than Calais.

But for the invasion to succeed,

the Allies had to ensure that the huge numbers of German troops

around Calais stayed where they were.

Because if they moved south and reinforced Normandy,

the breakthrough would not happen.

And D-Day might end in a bloodbath.

At Tehran in November 1943, the Allied leaders secretly agreed

that Normandy would be the invasion target.

Churchill turned to Stalin and remarked,

"The truth is so precious,

"she must be protected by a bodyguard of lies."

Thus was born the codename

for the great D-Day deception, Operation Bodyguard.

And Tar's spies would form the bodyguard of lies

to protect the Normandy invasion.

It did occur to me we could give them true information

laced with a certain amount of false information

and we were also able to build that up and introduce

a certain amount of strategic deception.

With his team of double agents,

Tar Robertson now went on the offensive.

He realised he could take Hitler's prized espionage weapons

and use them against him.

From his stable of double agents, Tar had selected the five spies

he knew were most trusted by the Germans.

They would each deliver to Hitler separate pieces of the jigsaw

to create the picture they wanted him to see,

an imminent attack on Calais of epic proportions.

If Robertson's gamble paid off, the prize was victory.

But if it failed and the plot was rumbled, then disaster loomed.

If just one of his double agents should prove a triple agent then,

instead of deceiving the Germans,

Robertson would be leading the enemy to the truth

and sending thousands of Allied troops to their deaths.

In February 1944, the arch gambler Churchill gave the go-ahead.

With three months to go until D-Day, the quintet went to war.

One of Tar Robertson's intelligence officers observed,

"I can't believe we'll ever get away with it."

First out on the road was Agent Treasure.

Her job was to cycle from town to town, collecting chickenfeed,

a mixture of truths, half-truths and downright lies

delivered piecemeal to her German spymaster.

I transmit a hodgepodge of badges, vehicles, tanks, planes

and airfields, garnished with conversations overheard,

from which the Germans cannot fail to derive the correct conclusions.

Her name was Lily Sergeyev. A Frenchwoman of Russian origin,

her story begins two years earlier in a Paris cafe.

As always, she was beautifully dressed

and accompanied by her beloved pet, a terrier called Babs.

Facing her was Major Emil Kliemann,

a senior officer in German military intelligence.

Vain and excitable, Kliemann was enchanted by Lily.

She told him she wanted to spy for Germany

and when he asked her why, her answer was enigmatic.

"I could tell you that I love Germany or I hate the British,

"but if I was here to spy on you,

"do you think my answer would be any different?"

Kliemann was intrigued and gave her the job.

He would send her to spy in Britain, travelling via neutral Spain.

But if he had read the diary she was secretly keeping,

Kliemann would have discovered that she was an unstable woman

whose only loyalty was to her pet dog.

LILY: Babs lifts up his shaggy truffle-like nose and looks at me enquiringly.

And I say in his pink ear,

"It's a grand game but if we lose, we lose our lives."

Once in Madrid, Lily knocked on the door of the British Embassy

and immediately offered her services to the Allies as a spy.

She claimed her hold over Kliemann would make her an ideal double agent

once she got to Britain.

But there was a catch. Treasure insisted that Babs must come too.

LILY: You probably think I'm ridiculous. To you, it's just a dog.

But to me, it's Babs. And worth more than �1 million.

The demand ran slap into one of the most cherished institutions

of British bureaucracy, the quarantine laws.

Babs would have to stay behind.

Lily threw a tantrum, but in the end, a compromise was reached.

Babs would be held in quarantine in British Gibraltar,

with the promise that the dog would join Lily later in England.

She handed him over to a British official, said her goodbyes,

and boarded the plane for England.

Robertson knew that Lily might be a recipe for trouble,

but an agent with a direct link to a senior German intelligence officer

could be priceless.

But what was Lily up to?

Had she always intended to work for the British

when she became a German spy? Where did her true allegiance lie?

And might she switch sides again?

LILY: Tar Robertson said to me, "I think there is no doubt

"that the German intelligence people have complete confidence in you."

"We can pull off what is known in the trade as an intoxication."

It's the sort of thing intelligence men dream about.

Lily had expected life as a spy to be glamorous and exciting.

Tar Robertson quickly put her straight.

He installed her here in a quiet block of flats in West London.

He appointed MI5's only woman case officer to keep an eye on her.

Mary Sherer was solid, unromantic and resolutely English.

Everything that Lily was not.

Mary always had a rather stern expression

and she would stare at you

in a very meaningful way.

One of her favourite expressions was, "Stupid man"!

Mary always had a dog.

So she would very much have been sympathetic to Lily's position,

but I would say otherwise they were probably

fairly diametrically opposed.

LILY: I still cannot quite place her.

Is she my jailer or nursery governess or what?

I don't even know what she feels about me,

though I suppose this doesn't matter very much.

If only I could have my Babs here.

I have a feeling that everything will turn out all right.

I think it's disgraceful the way they have behaved.

Agent Treasure was just one element in the grand deception

now been laid out across the country.

The Germans needed to be convinced that the Allied spearhead

was pointing at Calais.

In order to create the deception,

a vast American army was assembled in Kent,

poised to attack Calais across the Straits of Dover.

Had any spy planes been watching Kent,

they would have seen a formidable invasion force gathering.

From a distance, it would look strong enough

to break through the Atlantic Wall.

But close up, it was a different story.

To bolster the illusion of strength, large numbers of inflatable tanks

and dummy aircraft were assembled in the Kent countryside,

which would look like the real thing to German reconnaissance planes.

We'd created an imaginary army and we gave the Germans

the impression that we had available almost twice the number of troops

that were, in fact, in existence.

To lead this bogus army, a real general was appointed,

the legendary pistol-toting victor of the Sicilian campaign, George Patton.

An inspired choice because Hitler regarded the American general

as his most formidable adversary.

One of the lessons one learns in putting over a deception plans

is not to explain it to the Germans,

not to detail it, but to give them a mass of information

from apparently different sources which enables them

to put the jigsaw puzzle together and draw their own conclusions.

MORSE CODE

One of Tar's agents was a Spaniard, a master of invention

with an army of spies at his command.

Juan Pujol had a diploma in chicken farming, an overactive imagination

and a deep-seated hatred for Hitler.

A natural performer and a man of many guises,

Tar Robertson codenamed him Garbo.

He launched his campaign from an anonymous semi-detached house

in the northern suburbs of London.

Astonishingly, he had convinced the Germans

that he was a committed Nazi

with access to high level British intelligence.

And he did not act alone.

Garbo recruited no less than 27 sub agents.

These included an Army sergeant,

an English secretary,

a waiter from Gibraltar,

a travelling salesman,

two Venezuelan students

and a disgruntled seaman from Swansea.

But perhaps the most extraordinary part of the Garbo network

was the Brothers of the Aryan World Order,

a group of fanatical Welsh fascists.

Needless to say, none of these people existed.

All 27 had been invented by Garbo.

Garbo, on behalf of his 27 fake subagents,

sent more than 500 wireless messages,

each one reinforcing the fiction

of a vast American army assembling in Kent.

His imaginary network spanned the country.

The lies from each agent reinforcing the lies from the others.

An illusion made all the more convincing after one agent

who knew too much was suddenly eliminated from the spy ring.

It was a massive undertaking and the stakes could not have been higher.

One slip and the entire network

would be revealed for the sham that it was.

Unknown to Garbo or any of Robertson's double agents,

the German response to every message sent was being monitored

by the Allies biggest secret, the codebreakers of Bletchley Park.

German signals decoded at Bletchley

word for word, all the way to Berlin.

In German minds, the Welsh fascists and the rest of Garbo's network

were entirely reliable and their reports were swallowed whole.

German reinforcements poured into Calais to prepare for an invasion.

The ruins of Hitler's Atlantic Wall

still litter the landscape around Calais.

A system of almost impregnable concrete casements

that once bristled with guns.

They were built by forced labour

for a regime that believed it would last 1,000 years.

The bunkers were a warren, lived in by hundreds of men.

And deep inside these fortresses can be found a testament

to the Nazi's belief in their invulnerability.

Down here in the bunker, there's lots of graffiti showing

just how confident the Germans were.

There's one here that's addressed to WC, Winston Churchill,

"Whoever is bad must be punished and now you must pay for the bad thing you have started."

And there's another one over here, a sort of two-faced caricature

of Churchill himself. On the left, he's looking very smug

and out of his mouth is coming the word victory.

On the right, he's looking terrified

and the cigar has dropped out of his mouth and he is saying SOS,

the international distress signal.

Several hundred miles to the north of Calais,

another deception was under way.

While Garbo was busy inventing one army,

another was being created up on the east coast of Scotland.

This was the work of the third of Robertson's spies, Agent Brutus.

Roman Czerniawski was a deeply patriotic Polish fighter pilot,

a professional soldier who had devoted himself

to becoming an expert spy.

A complete world of literary fiction was created.

There were events which never took place.

Whole units, all kinds, starting from regiments

to divisions in armies were created.

People who never were born,

the generals, English or American, never existed.

Thousands of signposts were put all around, but really,

there were no troops here, no units,

in this beautiful, quiet countryside, like it is today.

His espionage career began when Poland was invaded.

He then fled to France and began working for the Resistance

and spying for the British.

My father would casually walk down the street,

wearing his French beret, an overcoat,

clutching a stick of French bread,

and in his right-hand pocket, he had a little stubby pencil

and a notepad and he was very, very carefully

noting down the insignia

on German uniforms and he would scurry home to his flat

and then radio back to London what he was seeing.

But he and his network were betrayed and captured.

The Germans then offered Czerniawski a stark choice,

spy for them on the British or see his comrades executed.

There was a very powerful moral code

that drove what he considered to be right or wrong conduct.

In those crucial few months when he was negotiating

and bargaining for his own freedom and the freedom of his agents,

he believed overwhelmingly that what he was doing was right

and good and in the interests of the country that he loved.

To save the other members of his network,

Czerniawski agreed to become a double agent against the British.

But he had another trick up his sleeve.

When the Germans faked his escape and sent him to Britain,

he immediately turned himself in and began working as a triple agent.

Tar named him after the ancient Roman turncoat, Brutus,

and appointed Hugh Astor as his case officer.

We decided that Brutus could be a principal channel for deception.

As a cover, he took a job

working with the Polish Army exiled in Britain.

Occasionally, I'd send him out on an espionage mission

to see what he could pick up. In the space of two or three days,

he'd come back with the most extraordinary amount of information.

He had drawn a map showing where all the different units

were stationed, identification signs,

very often the commanding officer's name and then I would use that

as the basis of a report to send to the Germans,

but changing the identity of various units which he identified.

As a professional soldier, Brutus's reports carried weight in Berlin.

The army he now invented in Scotland was intended to do

precisely the same thing as the fake army in Kent.

By threatening an invasion of Norway,

it might keep the occupying troops bottled up there

and away from the real battlefields in Normandy.

Brutus did not always send the messages himself.

He had his own Polish operator who would transmit for him.

Radio operators are always known as pianists and so his radio operator

was codenamed Chopin, which seemed appropriate for a Polish pianist.

Transmitting telegraphese is very much like handwriting,

it can be identified.

I would follow, as far as possible, his procedures

but substituting imaginary units for the real ones.

So now, two fake armies had been conjured into existence.

One in Scotland and the other in Kent.

Meanwhile, the real invasion army was beginning to mobilise

in southern England for the biggest amphibious assault in history.

150,000 Allied troops were secretly heading south towards Southampton.

The entire Allied Force was to be risked in one all-out assault on France,

to be led by the supreme commander, General Dwight Eisenhower.

The stage is being set for the beginning of a great and crucial test

all over the world.

I am completely confident that the soldiers, sailors and airmen

will demonstrate once and for all that an aroused democracy

is the most formidable fighting machine that can be devised.

I don't think we had a mental image of an enemy, we had a mental image

of the Nazi party and what they were doing.

They were the enemy. They were terribly bad people.

And somebody'd got to stop them.

As part of Operation Bodyguard,

Lady Dundas worked at General Eisenhower's headquarters.

The goal was clear, but the D-Day secret

was so precious, not even those risking their lives

knew where the invasion would take place.

Only the top brass could know the whole truth.

To provide Hitler with convincing information apparently gleaned from the highest quarters,

Robertson played the most unlikely card in his hand -

a bisexual Peruvian playgirl

with the unimprovable name of Elvira Concepcion Josefina de la Fuente Chaudoir -

the daughter of a guano magnate from Lima.

An international party girl with a penchant for gambling and the high life,

Elvira was slow to make her mark

when recruited by British intelligence,

who had sent her on a mission to charm her way into the German Secret Service.

She ended up on her natural playground, the south of France,

and then felt rather embarrassed and guilty

that she hadn't done more work

and she was rather enjoying sunning herself.

And she was a great gambler and a very good card player.

She was a great poker player.

She was approached by a German who she'd befriended, I think, in the casinos,

and he asked whether she'd be willing to work for him in England.

And after a good deal of thought, she said, yes, she would.

Back in Britain, her task was to haunt the cocktail parties

and casinos of high society London,

and send back to Germany an intoxicating mixture

of invented secrets and gossip,

reporting conversations she had never had

with people she had never met.

Churchill had ordered that no code name should give a hint at an agent's true identity -

a rule that the XX team cheerfully and consistently ignored.

Treasure was valuable, Garbo, a great actor.

And Elvira, the good-time girl, was given the codename "Bronx" -

the name of a particularly lethal cocktail.

Bronx sent her messages not by wireless, but by post -

writing to her German spymaster

between the lines of ordinary letters

using a matchstick impregnated with secret ink.

Using the impregnated match, secret, invisible messages

could be written over ordinary correspondence.

Once in enemy hands, the ink would be chemically developed

to reveal the key information.

Samples of Bronx's letters have been released to the National Archives in Kew.

Tell me what we have here in this file.

Well, this is the file of Bronx,

one of the double agents,

and it includes a whole range of documents relating to the way

she was controlled in the United Kingdom,

but also some of the texts of some of the secret messages

that she sent to her German controllers.

What is this, Mark? This is a photo taken by MI5 of the secret message

which was written underneath a cover message.

In capital letters, she's written,

"Last week, I saw a man unload a lorry full of foodstuffs

"into an old empty house next to the church at Roehampton."

It's not exactly going to change the war, is it?

No. I mean, you're not going to give all your best stuff at once, either.

And it's a way of stringing people along.

There's a bit of a Boy's Own Paper ring to the idea of secret ink.

Was it important in the Second World War?

Yeah, and it had been since the First World War.

But, I mean, the point about this sort of means of communication is it just took an awfully long time,

cos it's going to take the best part of two weeks to get there, probably.

So it's a kind of cumulative effect, her traffic?

Yeah, and it's also making the best of what you have.

If you don't have wireless communications, how do you do it? No mobile phones in that time.

As the days counted down to D-Day, Bronx would need a way

to get messages to her German spymaster much faster.

We intercepted a movement order to a German Panzer division -

which at that time were stationed near Bordeaux -

to move to the Normandy area.

Which was exactly what we didn't want.

And, really, without very much hope of success,

I said that I'd try and use Bronx to prevent the division moving.

The tanks would be in Normandy within days,

unless Bronx could convince her spymasters that they were needed more urgently elsewhere.

Now...

secret ink was not Bronx's only way of communicating with her handler, was it?

Oh, no, there were sort of crash messages, if you like,

that were conveying an innocuous... A telegram, for example, conveying an innocuous message

had a prearranged significance to her controller.

And therefore, you could get a certain degree of immediacy to it,

but again, you had to be very careful about what you did and didn't say.

Because it says, "Envoyez vite cinquante livres. Besoin pour mon dentiste."

"Send quickly �50, I need it for my dentist."

But that actually meant...

It actually warns there's going to be an invasion in the Bay of Biscay.

I must confess, I was astonished, within hours,

seeing this message relayed to Berlin.

Within 24 hours, an order cancelling the movement order for the...

I think it was the Panzer division.

I think it was the 13th Panzer Division, but I'm not sure.

And so, nobody was more surprised than myself, I must confess.

Back in England, Allied troops were making final preparations for the invasion.

To further convince the Germans that Calais was the target,

bombing raids on the area were stepped up.

And Tar Robertson was feeling a deep satisfaction

with the work of his spies.

The elaborate hoax seemed to be working.

Operation Bodyguard was on course.

He now felt confident enough to send a message to Churchill,

pointing out, "My double agents have, at a critical moment,

"acquired a value it is scarcely possible to overestimate."

PLANE ENGINE DRONES

But the drive home the D-Day lie, Robertson needed an agent

brave enough to make direct, personal contact with the enemy.

Anybody who goes into the field is courageous,

and the Germans were very rough on these people when they caught them.

The risk of being caught was quite high.

Lisbon, in neutral Portugal, was a hotbed of wartime espionage

and a regular haunt of Dusko Popov -

a flamboyant international dealmaker from Dubrovnik.

But his business was simply a cover. He was a British double agent,

codenamed Tricycle, working directly for Tar Robertson.

Tricycle was just the man to inject the great deception into the heart of German intelligence.

When I was with the Germans,

I tried to play the part that I am a real German spy.

Cos, in that kind of work, you're allowed one mistake,

and that's the last one you ever make.

He was really entering the lion's den

on every occasion that he travelled back to Lisbon.

He could've been betrayed at any time.

Since he had to deliver information first-hand

rather than use the wireless, he... I mean, charm came into this.

He had a lot of self-confidence and he was a very charismatic person.

He had trust in his ability to convince the Germans

that he was loyal to them.

He was taking a huge gamble, but it was a calculated one,

because his German spymaster was also a British double agent.

Johnny Jebsen was a senior German intelligence officer,

and at the start of the war, he had recruited his friend Popov to spy on the British.

They shared a taste for parties and women,

and indulged this to the full whenever they met up in Lisbon.

But secretly, Jebsen also shared Popov's hatred for the Nazis.

Jebsen was probably very similar to Dusko in his way to gamble with life.

They were best of friends since university days,

so I think that friendship was really key.

But the close friendship between Popov and his German controller, Jebsen,

was starting to worry MI5.

It became apparent that his German controller

knew that he was working for us, and this created a new dimension.

I was rather gung ho at that time

and felt that we ought to eliminate his controller,

but wiser counsel prevailed and we didn't.

Instead, Popov told MI5 that Jebsen was anti-Nazi

and should be brought in as another double agent.

Jebsen was recruited as Agent Artist.

Johnny was their best source of information

in the German Secret Service.

He was also able to protect Dusko.

At one point, they became so important

that if either of them was uncovered

it could mean the whole deception plan would be lost.

As Popov flew back and forth between London and Lisbon,

Jebsen was able to provide him and the British with a wealth of information,

secured from his position deep within the German war machine.

Secret weapons, military production,

and the innermost workings of German intelligence.

And he did more.

He also revealed the identities of Germany's top spies operating in Britain -

information that would enable the British to catch them.

The problem was these were the very spies under Robertson's command,

each responsible for a part of the deception.

Only a small number of people knew the whole detail.

I mean, some would know the place, others would know the date,

others would know the composition of the invading force.

But very few people knew the whole story.

Since Robertson's spies continued to report to their German spymasters without being arrested,

Jebsen came to the obvious conclusion -

they were all double agents,

and the Germans were being deceived on a MASSIVE scale.

Jebsen was now in on the secret, and MI5 knew it.

They were very much worried about Jebsen.

Jebsen could have betrayed the whole deception plan.

If he had been caught, all the others would have fallen.

Bletchley Park intercepts also revealed that Berlin was suspicious.

Jebsen was asking too many questions and was now under investigation.

MI5 had every reason to be alarmed.

Agent Artist knew the D-Day secret, and now,

the Gestapo were closing in on him.

Which left Tar Robertson with an appalling dilemma.

If he extracted Jebsen from Lisbon and brought him to the safety of Britain,

the Germans might realise their messages were being read.

The secret of the Bletchley Park codebreakers had to be protected at all costs.

But if Robertson left Agent Artist to his fate,

there was a real risk the Gestapo would arrest him.

Once he was in their hands, how long would he hold out before he cracked,

and expose the entire D-Day deception?

But then, another problem appeared...

in the shape of a small dog.

For months, Agent Treasure had badgered MI5

to fulfil their promise and bring her pet dog to Britain.

But Babs remained in quarantine in Gibraltar.

Increasingly angry, Treasure demanded that the Royal Navy

send a submarine to pick up her dog.

'I admired them. I trusted them.

'I had faith in British fair play.

'So they promised me in Madrid,

'but when they got me to London, they refused!'

And then, just when it seemed that relations between MI5 and Treasure couldn't get any worse,

news arrived that Babs had been run over by a truck.

TYRES SCREECH AND HORN BEEPS

CLATTERING

Treasure was heartbroken and furious.

She immediately accused Robertson and MI5 of murdering her pet dog,

and perhaps she was right.

A clue may lie in her MI5 case files.

LILY: Losing Babs I find very hard to accept.

I am alone. Absolutely alone.

The index contains no less than nine separate items relating to Babs.

"Letter to Treasure from Gibraltar about the welfare of her dog."

"Note on quarantine regulations with regard to Treasure's dog."

Every single one has been removed from the files and destroyed.

The mystery of Babs' death may never be solved,

but its consequences were potentially catastrophic.

LILY: I can destroy the work of three years.

Just a double dash and the Germans will know that I work

under the control of the Intelligence Service.

Treasure had kept one vital secret from her British handlers.

Emile Kliemann, her German spymaster,

had instructed her to insert a coded warning into her radio messages if she was caught,

to alert him that she was being controlled by the British.

LILY: This is my revenge.

They made me a promise.

And they didn't keep it.

Now, I shall have them in my power.

In Lisbon, meanwhile, events were moving with terrifying speed.

Johnny Jebsen, Agent Artist, was summoned to the offices

of German counter-intelligence in Lisbon to receive a medal

for his services to the Third Reich.

But there, his luck ran out.

He was ambushed, drugged

and smuggled out of Portugal.

Jebsen was driven across the border to France and then on to Berlin.

He was held at the Gestapo torture chambers

and interrogated there.

I wouldn't have wanted to be captured by the Germans.

I think they were very rough.

The number of agents who died in German hands...

and tortured.

Back in London, Tar received a three-word message from Lisbon.

It was the message he had been dreading.

"Johnny has disappeared."

MI5 was swept by near-panic.

Tar Robertson called a crisis meeting -

should they shut down the entire XX operation,

or could they continue as if nothing had happened?

It was no longer safe for Popov to act as a double agent.

I don't think, at that point,

he was wondering or worrying about the deception plan at all.

I think, here was his best friend being abducted by the Gestapo.

Most people didn't think Johnny would be able to resist interrogation.

They all thought that he would crack under physical torture.

People would have thought, you know, "That's it. The game is ended."

The fate of Johnny Jebsen

and the destiny of thousands of Allied soldiers

weighed heavily on Tar's shoulders,

and then the ghost of Babs the dog came back to haunt him.

And now, at the worst possible moment,

Agent Treasure threatened to blow the entire double agent system.

Treasure finally admitted that she HAD agreed

a secret signal with her German spymaster,

to be inserted into her messages should she ever be caught.

She confessed that her motive was revenge for the death of Babs.

But she refused to say what the secret signal was

or whether she'd already sent it.

Robertson confronted Lily and demanded to know what was going on.

He made it very clear that if she had betrayed the cause,

he would take the most severe action.

Agent Treasure was shut down immediately,

but it was too late to stop the invasion.

The troops were ready to go.

The date was set. The target was fixed.

All Tar and his team could do was continue to drive home the deception,

and pray that Jebsen didn't crack too soon.

Day and night, Bletchley Park's codebreakers anxiously scanned

hundreds of intercepted signals for any scrap of information

that might reveal whether the Germans had found out the truth.

The other agents flooded the Nazis

with messages confirming an imminent attack on Calais.

The days leading up to Overlord were very, very tense.

We were all working a sort of 24-hour day,

and wondering what questions

the Germans were going to ask next, how we would answer them.

Would they be believed? Would our agents become discredited?

It was quite tense.

But was Hitler listening?

Hitler's absolute control over his armed forces

meant that his was the only decision that really mattered.

Whether or not he believed the D-Day lie

would make or break the Allied invasion.

Just before D-Day,

Hitler met the Japanese ambassador, Baron Hiroshi Oshima.

The Fuhrer was keen to talk about the invasion and his knowledge of Allied plans.

Impressed, Oshima immediately radioed back a report of his conversation to Tokyo.

Two days later, the report, decoded and translated,

landed on Robertson's desk.

Hitler was adamant.

"They will come forward, all out, across the Straits of Dover."

The target was Calais.

HEAVY GUNFIRE

On June 6, 1944, the Allied troops,

under the command of General Eisenhower,

stormed the Normandy beaches

and took the Germans completely by surprise.

Over 10,000 Allied troops fell on the first day of the invasion.

It was a high and bloody price to pay,

but a fraction of the casualties there would have been had the Germans been ready.

By the end of the day, the Allies had their first foothold in France.

But the job was not yet over.

As the Allies pushed on into France,

the unseen force of the D-Day spies fought alongside them.

We were able, up to a point,

to persuade them that the Normandy landings,

when they started, were a diversionary attack.

That the main force was still in East Anglia

waiting to go across the Channel to Calais.

We rather assumed that by D plus 10

the Germans would have realised that they were having their leg pulled.

In the event, things went much better than we'd expected.

23 days after D-Day, Garbo received a startling message.

The Fuhrer had decided that in recognition of his heroic efforts

in the service of the Third Reich,

Garbo should be awarded the Iron Cross -

Germany's highest military honour.

Unbelievably, the D-Day lie was still holding.

As late as July, more than a month after D-Day,

no fewer than 22 German divisions,

almost a quarter of a million men,

were still held back in the Calais area.

In Norway, German sentries anxiously scanned the horizon

waiting for the attack from Scotland

that also never came.

The hoax had been more successful than anyone would've dared predict.

The liberation would be slow and costly.

But after the landings of June 6, victory was in sight.

CHEERING

Amid the celebrations on VE Day in May 1945,

few people raised a glass to Tar Robertson and the spies of B1A.

The work of the XX team would remain secret for years after the war.

But recently declassified files reveal the full impact of the deception operation.

This captured German map showed where the Nazis believed

Allied forces were positioned immediately before D-Day.

The map corresponds precisely with the lies fed to German intelligence

by the D-Day spies.

The deception saved many thousands of lives,

and was the equivalent to quite a large additional army force.

Their counterparts in German intelligence never guessed

the massive hoax Tar and his team had pulled off.

Or maybe some of them did, and just chose to ignore it.

Let us put ourselves in the position of a German controller with an agent in England.

Would you go to Hitler and say,

"I've been spending millions of Deutschmarks maintaining this

"organisation in England, and they're all a lot of dummies."

I mean, very difficult for him to do.

Hugh Astor carried on his work for MI5 in the Middle East.

But Tar Robertson left in 1949 and became a sheep farmer.

Some of the D-Day spies were recognised for their contribution,

and awarded medals in strictest secrecy.

Garbo was awarded an MBE -

an unusual honour for a man who had already received the Iron Cross.

Long after his fake agents had been laid to rest,

Garbo visited the Normandy war graves.

I did all the things that I could...

..to save men, but I couldn't save these men here.

It is very sad for me to see this now.

Thousands more would lie in cemeteries like this,

had it not been for the work of Garbo and the other D-Day spies.

Agent Treasure had not gone through with her threat to expose the deception plan.

Perhaps, she had only ever intended to torment MI5 at a critical moment,

and that was a revenge for Babs.

She lived out her days in the suburbs of Detroit,

surrounded by dogs.

Bronx, the bisexual Peruvian party girl,

opened a souvenir shop in the south of France.

Brutus remained in England, but his love for Poland never dimmed.

He became active in Polish politics, but it was not until old age

that he spoke openly about his wartime activities.

I grew up with the stories of him skiing and him being a pilot,

and anecdotes of him being parachuted into occupied France.

It's exciting to know that the stories that I grew up with were actually true,

and that those stories were part of a bigger story in which he was central.

And that does make me proud.

Dusko Popov, Agent Tricycle, returned to business,

eventually retiring to a house in the south of France,

where he wrote his memoirs.

I went...

a few dozen times to meet the Germans.

I never felt absolutely certain that I shall come back.

And it would be lying now to tell you that I wasn't afraid.

I was actually terrorised from the first day to the last.

His house is still the family home.

Popov died in 1981, wondering to the end

just what had happened to his friend Johnny Jebsen.

These men did extraordinary things during the war,

and I think the war called for them to rise to that event.

And they took chances probably people wouldn't take during peacetime,

but the times called for it. It was war.

The fate of Johnny Jebsen, Agent Artist, is shrouded in mystery.

In early 1945, he was moved to one of the most notorious concentration camps in Germany.

And two months before that camp was liberated,

the Gestapo came to collect him.

He was never seen again.

Johnny Jebsen could have turned history in a different direction and survived,

but he chose not to.

Like many ordinary, flawed people, he didn't know his own courage

until war revealed it.

Agent Artist, Johnny Jebsen, was not a conventional D-Day hero,

but he was a hero nonetheless.

Subtitles by Red Bee Media Ltd