The capture of Hitler's deputy after he parachuted into Scotland during the Second World War remains one of the strangest episodes of the war.

The Nazi leader's right-hand man Rudolf Hess flew to Britain in a secret attempt to broker a peace deal in May 1941 but was forced to bail out of his plane.

He was captured and jailed as a prisoner of war and put on trial when the war ended, before being sentenced to life in Spandau prison in Germany in 1947.

Now newly-released files have revealed that officials were engaged in a behind-the-scenes battle against claims the man who was jailed was actually an imposter.

Newly-released files from west London's National Archives revealed officials were engaged in a behind-the-scenes battle against claims the man who was jailed was not Hess (pictured) but an imposter

By 1979 Hitler's deputy had been behind bars for almost four decades after flying to Britain in 1941 on a bizarre one-man peace mission to end the Second World War.

However a former British Army surgeon who examined him in Spandau Prison claimed the man was an imposter and accused the British government of a cover-up.

Dr Hugh Thomas said Hess's plane had been shot down on take-off from Germany on the orders of his rival, SS chief Heinrich Himmler, and that someone else was in the plane.

Although the theory did not gain traction, secret National Archives files show that Foreign Office officials fought to counter the claims.

'We are at present under no pressure to comment on the allegations and there is obviously a danger that any attempt by HMG to refute them will only focus attention on them and lead to a public debate between Dr Thomas and HMG,' they wrote.

'On the other hand, if no refutation is published, the allegations could conceivably be revived in future, perhaps after the death of Hess.'

Behind the scenes officials quietly commissioned a series of reports countering claims in the book.

Behind the scenes: Dr Hugh Thomas said Hess's plane had been shot down on take-off from Germany on the orders of his rival, SS chief Heinrich Himmler (pictured), and that someone else was in the plane. Although the theory did not gain traction, secret National Archives files show that Foreign Office officials fought to counter the claims

One was testimony from a British physician at Spandau who testified that the man in prison had scars that corresponded to wounds Hess was known to have suffered in the First World War.

Two further reports were prepared to prove his plane could not have made the long flight from Germany to Scotland.

The Foreign Office then published a response stating: 'On the basis of these studies, we have no doubt the prisoner in Spandau is Rudolf Hess.'

Britain and its Western allies pressed for his release on humanitarian grounds from the 1950s onwards, but the Russians refused.

In 1987, the 93-year-old Hess was finally found hanging at the prison. The official verdict of suicide was rejected by Hess's son, who claimed he was murdered.