Bernard Gray, a well-known British war reporter whose death in the second world war had long remained a mystery, perished in a submarine which had left Malta for Alexandria from Malta, it has been revealed.

Mr Gray has been described as the only unofficial "submariner" and journalist to lose his life in a British boat.

He was killed with 43 other men on board HMS Urge on its way from Malta to Egypt in April 1942.

His fate was finally uncovered last Friday at the request of his grandson through an inquiry by the Royal Navy Submarine Museum in Gosport, Hampshire.

He was revealed as the only unofficial passenger to sail on a British submarine in World War Two and the only journalist to die in one, according to reports in the British media.

Some records in the past had suggested that Mr Gray was killed in the Middle East.

"My own darling," he had written to his wife an hour before he sailed, "I'm going away now on a trip which is dangerous. It's the last thing of its kind I shall ever do. I'm doing this for the children."

His promise turned out to be true; it was his last trip. Mr Gray - who was renowned as "the man who goes everywhere" - ended up at the bottom of the sea, The Guardian newspaper wrote.

Working for The Sunday Pictorial, a now defunct Mirror Group newspaper, he lived up to his reputation as a "richly piratical" reporter by using well-placed friends to wangle his way on board HMS Urge.

Mr Gray covered the British retreat from Dunkirk, which was commanded by Lord John Gort who later became governor of Malta. Museum archivist George Malcolmson said it was possible that the journalist's contact with the governor secured his fatal place on HMS Urge.

He was eager to cover the Egyptian desert campaign, the war's biggest story at that time.

At the time, the seas around Malta were also a big battleground. Just weeks before its demise, HMS Urge had sunk Italian cruiser Bande Nere north of Sicily as the German and Italian bombing led to the loss of numerous ships including four destroyers and four submarines.

Urge was lost on April 28, 1942 in unknown circumstances.

After Mr Gray disappeared, the navy told The Sunday Pictorial executives only that he had left Malta on an unnamed submarine. A year later, solicitors for his family pleaded with the Admiralty for information to help them wind up his estate.

Eventually the solicitors received an unsigned letter purporting to be from the Admiralty, which said: "Unofficial inquiries show that he almost certainly took passage in HMS Urge for Alexandria and was subsequently lost. No evidence of his survival has been found".

After recent checks, the museum decided that the letter proves the circumstances of Mr Gray's death and added his name to its records.

Navy News, the online version newspaper of the Royal Navy, said it is thought his name may have been purged from the records. The loss of the submarine was not made public for some time in order to spare the British population more bad news and to avoid the sinking being used by the Axis forces as a propaganda coup, the online newspaper said.

Mr Malcolmson said correspondents were known to have gone on missions with submarines but had usually gone through the official procedures, which made Mr Gray's death almost certainly unique.

"There is nothing on him in our files on HMS Urge and to the best of our knowledge he is the only non-submariner lost at sea during World War Two."