A 21-year-old seaman who lived with his mother in Greenock was prepared to put at risk the lives of thousands of seafarers through lust, greed, and the promise of personal aggrandisement if Germany won.

The secret MI5 papers published today reveal that Duncan Alexander Croall Scott-Ford almost certainly caused the loss of several ships and many lives.

He was hanged at Wandsworth prison in 1942 after a secret trial at the Old Bailey.

Until today little has been written about Scott-Ford, although the MI5 papers make it clear that he is one of the most dangerous traitors ever to be brought to justice.

One report declares that there were degrees of infamy, and Scott-Ford was probably worse than Roger Casement, considered at the time to be the epitome of evil.

In at least five meetings with Nazi agents at ports abroad, Scott-Ford handed over details of convoy movements which then became the targets of German U-boats. A notebook containing details of convoy routes was found on him when he was arrested.

In return he received money, women, and a promise that he would run his own ship at the end of the war or a major UK port. He was also promised marriage to Ingeborg Richter, daughter of a leading Nazi, with whom he had become infatuated in June 1939 at Dar-es-Salaam when she was a stunning 17-year-old.

Interviewed over many hours at Camp 020, MI5's interrogation centre in South West London, Scott-Ford revealed the extent of his treachery.

One report says: ''He came here full of bombast, visualising himself an important figure in the international spy racket. During the course of lengthy and searching interrogation he was eventually shown to be the traitorous rat he is.

''I cannot find one single mitigating circumstance in this man's history or attitude towards life.''

Another report says: ''The damage of which Scott-Ford was capable was infinite.

''Death by hanging is almost too good for a sailor who will envisage the death of thousands of his shipmates without a qualm.''

Born in England, Scott-Ford joined the Royal Navy in 1937 as a writer. His treachery began two years later when he met Richter and gave her secret naval codes. Later in Alexandria he passed on cyphers to a prostitute in Alexandra, but this time was found out. He was dismissed from the navy and sentenced to six months imprisonment, but on his return to the UK was allowed to go free.

He went to live with his mother at 10 Bannockburn, Greenock, and set about re-establishing a career at sea, this time with the Merchant Navy, signing on with the SS Almenena at Glasgow.

His weakness for frequenting brothels almost certainly made him a target for German agents. However, his treachery was not uncovered until 1942 when another ship he was serving on docked at Lisbon. There he was followed by MI5 agents and on his return to Salford he was arrested.

Placed in a cell with a police officer in battledress who was posing as an army absentee, Scott-Ford prophesied: ''If they can prove I'm a spy, they'll send me on the eight o'clock walk.''