In soon to be published memoirs, Lord James Douglas Hamilton says no-one in Britain knew Hess had flown in to the country in 1941.

Hess, the Deputy Fuhrer, parachuted into a field near Eaglesham, outside Glasgow, intending to meet his father, the 14th Duke of Hamilton.

Lord James, the former Tory MSP for the Lothians, said: “There have been many conspiracy theories suggesting that it wasn’t Hess but an impostor and that the British Secret Service was involved in some sort of plot.

“But I have gone through MI5 papers thoroughly and it is absolutely clear it was an entirely German-driven affair and nobody in Britain had the faintest idea Hess was thinking of coming.”