A middle-aged Scottish scoutmaster trained the special operatives who destroyed Adolf Hitler's nuclear weapon programme, a new book has revealed.

John Skinner Wilson was 52 when he was asked to quit his post in the Boy Scouts movement to help select and train candidates Winston Churchill's covert outfit, the Special Operations Executive (SOE) during the Second World War.

His tough selection process is still used as the basis of all those used by British special forces organisations such as the Special Air Service and the Royal Marine Commandos.

Mr Wilson spent nearly 20 years working for the Boy Scouts after being recruited by the organisation's founder General Baden-Powell while Senior Deputy Police Commissioner in Calcutta.

Just as with scouting, the former policeman believed that anyone, however unlikely, could make the best undercover agents, the Times reports.

In his memoirs unearthed in the Imperial War Museum, he wrote: "No normal course of training can determine a man’s character.

"It is curious but true that some of the best recruits were thought at first not likely to make good agents, and one redoubtable member was almost rejected outright as unsuitable."

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After finding out Nazi scientists were trying to build nuclear weapons, Winston Churchill and US President Franklin D. Roosevelt decided all Nazi efforts in nuclear research must be sabotaged.

A key element of Hitler's nuclear programme was the Norsk Hydro plant in Nazi-occupied Norway which produced "heavy water".

Churchill green lit a force of 34 commandos to blow up the facility but the mission went terribly wrong with all involved either killed or captured.

The next attempt on the plant took the form of ten special operatives's trained by Wilson for covert action in Scandinavia.

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The men successfully parachuted into Norway, evaded capture and scaled a 600ft vertical, ice-bound cliff to gain access into the plant.

They successfully blew up the heavy apparatus and managed to escape with their lives.

Colonel Wilson was awarded an OBE and a Commander of the Royal Norwegian Order of St. Olav for his services.