HE served his country as a submariner.

But William Madley’s distinguished reputation as a former Royal Navy man is now in tatters.

The former Huddersfield man is currently languishing in a Spanish jail cell for the brutal murder of business colleague Derek Cowan.

Madley has been sentenced to 10 years in jail by a judge in Barcelona, Spain, after he admitted the killing, at an earlier hearing.

At the opening of his murder trial in Barcelona, Madley admitted striking Mr Cowan over the head with a bottle up to eight times before strangling him.

He was sentenced to 10 years at the end of his trial, which had to take place despite his guilty plea, because of Spanish legal procedure.

Mr Cowan, 46, from Larkhall, Lanarkshire, was killed in his flat in Barcelona in October 2008.

Madley, 47, was a former Faslane-based submariner originally from St Andrews, Fife.

He moved to Huddersfield as a young child with his family and went to schools in Huddersfield before joining the Royal Navy.

He told the trial that he had arranged to meet Mr Cowan to discuss a business deal.

But they began to argue about an old deal in which Madley had lost an 8000-euro investment.

Divorced father-of-two Madley, sporting a goatee beard and dressed in a white shirt and dark trousers, said: “In my anger, I picked up a bottle and hit Derek over the head.

“He fell to the floor after I hit him with the bottle and then I strangled him. I don’t know if he was dead or alive when I left the flat.”

Madley then went on the run but was caught four weeks after the killing.

Outside court, Madley’s defence lawyer Luis Borrell said: “He could have faced a more serious charge of premeditated murder carrying a sentence of 15 to 20 years if we had not reached this agreement.”

Madley also faces having to pay nearly 120,000 euros in compensation to his victim’s family.

Both Madley and Derek had been linked to ‘‘boiler room’’ scams in which worthless shares are sold.

Madley grew up in Deighton and still has family in Huddersfield.

According to a profile on the Friends Reunited website, he went to Bradley C of E Junior School, then the former Deighton High School and Greenhead College, Huddersfield, which he left in 1981.

He was 25 when he left Huddersfield.

From that point onwards he served on a series of Royal Navy submarines.

Between 1983 and 1985 he was based on the HMS Collingwood and from 1985 to 1986 he was on HMS Amazon.

In 1986 he was based on HMS Glamorgan before a posting on HMS Courageous from 1987 to 1989.

Property agent Mr Cowan, described by friends as a “wheeler dealer”, settled in Spain seven years ago.

He recruited Mr Madley as a partner in his firm – an intermediary service in big property deals – two years before his death.

But their relationship soured after a disagreement over money.

His body was discovered at his penthouse flat at Carrer de Bailen in the fashionable Eixample district of Barcelona.

He was found by another business partner Andreas Langweider.

Madley had set up a company called FinSA Management Group, an investment advice firm, with another English partner, Justin Box.

When Madley vanished after the killing a former schoolfriend, Sallie Barrett, of Huddersfield, said she was shocked to hear he was missing.

“I was at school at the same time as Billy.

“He was just a nice quiet lad. I hadn’t heard from him for years but just recently we had exchanged brief messages on the internet.”