Britain's most important double agent of the Second World War almost had his cover blown because his homesick wife could not stand living in England, according to secret files made public for the first time.
Juan Pujol Garcia - codenamed Agent Garbo by MI5 - was a Spanish national living in the London suburb of Harrow from where ran a network of fictitious sub-agents sending back a steady stream of false intelligence reports to his German spymasters.
His elaborate deceptions helped to convince the Nazis the D-Day landings would take place at the Pas de Calais - diverting German forces away from Normandy, scene of the actual invasion, saving countless Allied lives in the process.
However MI5 files released to the National Archives in Kew, west London, show how his scheming was nearly wrecked because his wife, Araceli, struggled to cope with the pressures of his double life.
Fears the deception could unravel if she was recognised by fellow Spaniards in London, meant that her movements were strictly controlled by Pujol and she was largely confined to the house with her two children, to her intense frustration.
Matters finally came to a head in June 1943 - a year before D-Day - when, after quarrelling violently with her husband, Mrs Pujol threatened to go to the Spanish embassy and tell all unless she was allowed to travel home to see her mother.
"I don't want to live five minutes longer with my husband," she screamed at Pujol's alarmed MI5 case officer, Tomas Harris. "Even if they kill me I am going to the Spanish embassy."
With a visit to Spain out of the question, Mr Harris suggested she should be told Pujol had been sacked as a result of her outburst, while quietly allowing him to carry on his work against the Germans under the cover of working as a BBC translator.
Pujol, however, felt rather more drastic action was needed if she was to be brought round. With the agreement of MI5 he came up with a deception plan every bit as cunning as those he used to fool the Germans.
The next day Mrs Pujol was informed her husband had been detained following a violent argument with his MI5 spymasters over her treatment - prompting what Mr Harris described in his report as a "hysterical outburst".
She then threatened to take the children and "make a disappearance". A MI5 officer who was sent to check up on her found she had turned on all the gas taps in the house in an apparent suicide attempt.
"He said he felt there was a 90% chance she was play acting, but there existed a 10% chance of an accident," reported Mr Harris, who sent over his own wife to comfort her.
The following afternoon, a tearful Mrs Pujol was taken blindfolded to MI5's Camp 020 interrogation centre near Ham Common, west London, where her husband was brought before her, unshaven and dressed in camp clothing.
In an emotional reunion, she swore to him she had never meant to carry out her threat to go to the embassy and had simply wanted her request to to return home to be taken seriously.
"She promised that if only he was released from prison, she would help him in every way to continue his work with even greater zeal than before," Mr Harris noted. "She left Camp 020 more composed, but still weeping."
The charade was not quite over. Mrs Pujol was then taken before MI5's legal adviser, Major Edward Cussen, who after a stern dressing down, told her he had decided her husband should be released and allowed to continue his work.
"He reminded her that he had no time to waste with tiresome people and that if her name was ever mentioned to him again, he would simply direct that she should be locked up," Mr Harris noted. "She returned home very chastened to await husband's arrival."
Mr Harris was clearly in awe at the way Pujol orchestrated the whole affair, writing: "The extraordinary ingenuity with which he has conceived and carried through this plan has perhaps saved a situation which might otherwise have been intolerable."