The claim originates from Ali Magoudi’s 2005 book Rendez-vous: La psychanalyse de François Mitterrand.
Magoudi was Mitterrand’s psychoanalyst between 1982 and 1984 and published the book several years after Mitterrand’s death. So, there’s the obvious ethical issues with a therapist spilling the beans on his patient’s private sessions.
Since he was dead, Mitterrand obviously never had the chance to respond to any of the book’s claims. Magoudi claims Mitterrand said about his conversation with Thatcher on May 7, 1982: “What an impossible woman. She’s threatening to unleash an atomic weapon against Argentina if I don’t provide her with the secret codes that will make the missiles we sold the Argentinians deaf and blind. [I gave them to her, rather than] provoke a nuclear war for a few islands inhabited by three sheep as hairy as they are freezing.”
From there, Magoudi claims Mitterrand was going to get “revenge” by building a tunnel under the Channel and that he boasted, I’ll succeed where Napoleon III failed.” There are, of course, some problems with Magoudi’s claims: No British politicians, diplomats, or military officers have ever mentioned the nuclear threat or the existence of the codes. No French politicians, diplomats, or military officers have ever mentioned the nuclear threat or the existence of the codes. The Chunnel quid pro quo makes no sense. Conservative government had been considering a tunnel scheme since 1979. In 1981, a year before the Falklands War, Thatcher and Mitterrand had begun seriously studying the Chunnel scheme. Both were enthusiastic about the idea and had strong domestic and foreign reasons to support the project. It wasn’t something Mitterrand forced down Maggie’s throat.
If the British had the codes, they don’t seem to have used them. Atlantic Conveyer was traveling with an escort of warships, but was still hit on May 25. HMS Glamorgan was hit by a land-launched Exocet as last as 12 June. The British were still planning extremely risky anti-Exocet operations well after May 7. Operation Mikado, a nearly suicidal plan for an SAS raid on Argentine airbases wasn’t scrubbed until late May. Hazardous pre-raid reconnaissance missions (Operation Plum Duff) were carried out in mid-May by heliborne SAS detachments.
It seems unlikely British commanders would have done these things if they had cheat codes in their pocket in early May. Bottom line. It’s very, very unlikely the story is true.
Answer from Bacarruda on reddit.com

