Document discovered by National Archives shows claim made after the war by recaptured RAF officer, but historians are sceptical

It’s one of the most celebrated heroic failures of the second world war – the “great escape” of dozens of allied prisoners of war from a German camp by tunnelling under the wire.

As loosely depicted in The Great Escape, a 1963 film, 76 British and international air force members successfully escaped from the Stalag Luft III camp in March 1944, only for most of them to be recaptured and 50 brutally executed.

Almost exactly 80 years on, historians re-examining wartime documents have uncovered a bombshell claim made by one of the escapers – that the murdered men were betrayed by two English Nazi collaborators.