An Ashford author is calling on the Government to re-open the investigation into a submarine which went missing more than fifty years ago.

Alan Gallop has joined forced with Labour MP for Hayes and Harlington John McDonnell in calling on the Ministry of Defence to re-examine why the HMS Affray was allowed to leave dock in an unfit condition.

The vessel had sailed from Gosport on a routine training exercise in the English Channel in April 1951.

The submarine, carrying a crew of 75, sent a signal that it was about to dive at 9.15pm on April 16.

But the vessel never surfaced, triggering the largest air-sea search operation ever mounted in Britain.

It was eventually found two months later in nearly 300ft of water off the Channel Islands.

It remains there today and has been designated an official military grave.

Mr Gallop, 58, who is due to launch his new book about the disaster, Subsmash - The Mysterious Disappearance of HMS Affray, said the Admiralty of 1951 did its best to cover up circumstances surround the loss.

"The submarine had a history of mechanical problems and should never have been sent to sea. Several crew members told their wives and families before they sailed that they has misgivings about its condition, although it has never been proved what happened to HMS Affray," he said.

Thanks to previously top-secret documents Mr Gallop discovered memos from the Admiralty criticising officers who passed the submarine fit for sea.

"Although the Admiralty of the day did everything possible to find the missing submarine, it was afraid that its reputation would be tarnished if it became known that they had allowed 75 men to go to their deaths in a vessel that was far from perfect."

He added: "They were economical with the truth, too, when it came to telling the Government about the submarine's condition. As a result, various ministers, including Parliamentary Secretary to the Admiralty (and later Prime Minister) James Callaghan unintentionally gave misinformation to other MPs in the House of Commons based on Admiralty briefings."

MP Mr McDonnell is now seeking an urgent meeting with Secretary of State for Defence, Des Browne and First Sea Lord and Chief of Naval Staff, Admiral Sir Jonathon Band to discuss re-opening the HMS Affray inquiry.

Mr Gallop's book is due to be launched at the Guildford Book Festival on Thursday.