The dossier also debunks one of the most enduring legends about the Fuhrer – the claim that he lost a testicle when he was injured at the Battle of the Somme. Morale-boosting ditty ‘Hitler has only got one ball’ was popular during the Second World War and his admirer Unity Mitford suggested he ‘lacked something in the manly department’.

But the American records, which feature in a Channel 4 documentary, show the dictator was not monorchid (the medical term for being born with one testicle). They also shoot down claims that Hitler was a predatory homosexual who massacred 150 supporters to hide his secret.