Roger 'FIDO' Grosjean was a French double agent who spied on the Nazis for MI5 but little did he know his glamorous English wife Angela 'Sallie' Cross was also spying on him

The story sounds like just another whirlwind wartime romance. Dashing French fighter pilot meets British beauty in a London club in 1943. They fall in love, she leaves her job and takes his name, they move to the country and she becomes pregnant.

Yet Roger Grosjean and Angela Cross were not who they seemed to be – not to the outside world and not to each other.

Roger was a double agent, codenamed FIDO, who worked for British intelligence while pretending to spy for the Nazis.

But he had no idea his glamorous English wife had also been recruited by MI5... to keep him under surveillance.

That, at least, is what their son believes after 10 years of investigations – and he wants the British security services to admit it.

Francois Grosjean is convinced his parents’ relationship was manipulated by MI5 and that he and his elder sister, who had disrupted, unhappy childhoods, were “the unwanted consequences of a James Bond spy story gone wrong”.

Most of the files on Second World War spies have been released to the National Archives – but MI5 still won’t acknowledge FIDO’s existence, even to his son.

Francois believes they are still covering up the way young women were used to charm and spy on agents.

Francois, 68, says: “British Intelligence is always covered in glory... the glamour of James Bond, the gentleman spies. But this story really isn’t very nice and two innocent children were caught in the fall-out.

“I think MI5 want to prevent the truth coming out – that young English women were used like this during World War II.

“But I still hope one day it will. I believe my sister and I have a right to know who our parents really were and how this all started. The impact on our lives has been immeasurable.”

Francois, who lives in Switzerland and is emeritus professor of psycholinguistics at Neuchatel University, knew nothing of his father’s spy work until 30 years after his death in 1975. Roger, who won the French Legion of Honour, had left the air force in 1946 and became an archeologist.

In 2004 his second wife gave Francois a box of old papers which began to reveal Roger’s part in the British Double Cross (XX) System – one of the greatest intelligence coups of the war.

When Francois asked MI5 for details he was told: “We are not in a position to say whether we hold a record for your father. Any record we might have would be unlikely to be releasable in the foreseeable future.”

His mother, originally called Angela, became a top fashion model in France then Italy’s first female racehorse trainer. When she died in 2009 her papers convinced Francois MI5 had asked her to snoop on Roger, either before or just after their romance began.

He explains: “She was from London and at 19 was a theatre stage manager. She was always a bit of an actress and later had a small role in a film with Elizabeth Taylor”

In 1942, when Angela married a man called Peter Cross, the Germans invaded the previously unoccupied southern area of France and French fighter pilot Roger began making plans to join Charles De Gaulle’s resistance forces in London.

Francois says: “He used the pretext of spying for the Germans, who wanted him to steal a plane and fly it back. But as soon as he arrived he told the authorities it was just a ploy and he wanted to fight for Britain. He was taken on by MI5.

“He used to write letters dictated by intelligence officers, supposedly love letters to a woman in Barcelona, with secret messages between the lines in invisible ink.It was all very James Bond. The messages were a mixture of genuine and false intelligence to convince the Germans he was still working for them while persuading them the D-Day landings would take place at Calais and Dunkirk not Normandy.

“Then, in October or November 1943, he met my mother, who was working at the Free French Air Force Club in London. He was 23, she 22. But did she ‘meet’ him or was she introduced to him for a reason? Was she working there to monitor these French allies for the security services?

“Things happened very quickly. After just a few weeks, in Jan­uary 1944, Angela changed her name by deed poll to the French sounding Sallie Henriette ­Grosjean, although she probably didn’t speak the language then.

“My father was sent to Caistor airfield in Lincolnshire where he was allowed to fly to make the Germans believe he was getting ready to steal a plane.

“But MI5 would have wanted him watched... just in case. Perhaps that’s why they ‘placed’ my mother in his arms.

“She went to Caistor with him. He spent some months there but in March was moved to an office job in London – just as my mother became pregnant with my sister. That is where the James Bond story went wrong. In the movies the Bond girls don’t get pregnant.

“MI5 probably decided just to let things happen. But in May everything stopped. MI5 realised my father wasn’t effective as a double agent – either his information wasn’t getting through or the Germans knew he’d been turned. So he was sent to Algeria and Morocco for six months as an instructor.”

Francois adds: “Sallie stayed in Caistor and my sister was born. Her marriage to her first husband was dissolved a month earlier and she and my father later married.

“From Morocco he was sent back to liberated France and worked at the Air Ministry until the end of 1946.

“With my mother still onside I think MI5 let her and my sister join him in Paris. Civilian travel to France was not possible until May 1945 but she went in March. Why the privileged treatment?

“My sister went to her paternal grandparents in Northern France. But three months later Sallie was pregnant with me, even though their relationship was not the greatest. I know from my father’s diaries and letters that he really, really loved my mother but I don’t think it was reciprocated. I think she was just doing a job.

“In January 1947, when I was nine months old, my father left. They’d been together only two and a half years. My sister and I were put into foster homes and families or cared for by nannies then packed off to boarding schools. I even spent vacations with friends’ families.

“We always knew we were not wanted and never understood why our parents had married.”

Francois, a family man who dotes on his first grandchild, adds: “Sallie never showed any affection to my father and often denigrated him in front of us.

“I think she felt trapped. She had an easy surveillance job but we came along and it got messy. She was a difficult, unpleasant person and very unkind.”

After his divorce Roger married again while Sallie became a star model for Paris fashion designer Jacques Griffe.

Later she met a rich businessman and moved to Italy where she began to breed and train horses. Francois was estranged from his mother but inherited her diaries and papers and began piecing together the story.

He said: “Since then, extensive evidence of my father’s role as FIDO has been published. He’s even mentioned in the diaries of Guy Liddell, MI5’s director of Counterespionage in the war.

“But MI5 refuse to release his file,
‘to protect former staff and agents’ most of whom, if not all, are dead.”

Francois appealed to a tribunal but it took MI5’s side.

He says: “I’m sure I am right about my mother too – but I only have circumstantial evidence so have not yet inquired about her.

“I fear the answer will be the same though. MI5 don’t want the truth to come out even after 70 years.

“Their embarrassment should be outweighed by the right of my sister and I to understand who our parents were and better understand ourselves.”

The Home Office said yesterday: “We do not comment on matters of national security. It is a longstanding policy never to confirm nor deny whether someone was ever an agent.”