He suffered horrific torture at the hands of his Japanese captors and when still John Fraser refused to betray his fellow prisoners he was beheaded.

Now a George Cross awarded posthumously to the Scot executed during the Second World War has fetched £228,000 at auction.

The decoration – the highest civilian award for gallantry – was presented to Mr Fraser’s widow by George VI in 1946.

Mr Fraser, born in Edinburgh in 1896, was killed in Hong Kong in 1943 after he doggedly resisted all attempts to make him reveal details of escape plans and secret communications with the outside world.

The medal – described as one of the most important and poignant gallantry awards of the Second World War – was put up for auction by his grandchildren, along with his leather suitcase containing a copy of the last letter he wrote to his wife Kathleen.

It was bought by an anonymous bidder in the London auction room of Dix Noonan Webb for £228,000 – exceeding its pre-sale estimate by £100,000.

Mr Fraser, who won the Military Cross and Bar during the First World War, was a Civilian Defence Secretary in Hong Kong and a member of the Executive Council in the British colony.

Following the fall of Hong Kong to the Japanese, he was interned but organised escape plans and a clandestine wireless service, and succeeded in receiving news from outside and getting important information out.

Mr Fraser, who was educated at Edinburgh’s Trinity Academy and then Edinburgh University, was eventually arrested and subjected to prolonged torture by his captors.

His medal citation states: “Under this treatment he steadfastly refused to utter one word that could help the Japanese investigations or bring punishments to others.

“His fortitude under the most severe torture was such that it was commented on by the Japanese prison guards.”

George Wright-Nooth, a Hong Kong police officer who smuggled food and messages in and out of the camp, later wrote in his memoirs of Mr Fraser’s “incredible courage”.

He recalled: “He was a small, somewhat mild-looking civil servant. He went to his death crippled by torture and beatings, his body emaciated and bent, virtually unrecognisable as the man he had once been.

“His was the triumph of the spirit over physical torment.”

Mr Fraser and 32 others – including one woman – were sentenced to death after a show trial.

The civil servant’s wife had been evacuated from Hong Kong with their sons before the Japanese attack.

On the day of his execution, Mr Fraser, knowing his fate, wrote to his wife: “My dearest darling. This is my last letter... Give the boys a good education and make them learn a trade or profession.

“Remember the only thing I cared about was you and the boys. My dearest love to you and Tom and Ian.”

The letter was discovered, with the rest of his effects, in a battered suitcase returned to Kathleen after the war.