MURDER squad detectives based in Torbay, Devon, last night flew from

RAF Brize Norton to the Falkland Islands, to investigate the

disappearance of a Royal Marine -- 18 months before the outbreak of war

with Argentina.

''A lot of people on the Falklands have been harbouring a secret for a

long time and we are now hoping that we can get to the bottom of it,'' a

spokesman for Devon and Cornwall Police said yesterday.

''We are not sending officers on an 8000-mile journey for nothing.''

Marine Alan Addis, 19, from Hull, went missing on a remote settlement

of the Falklands 15 years ago.

Police hope the sacrifice of British troops in retaking the Falklands

might encourage islanders to search their consciences and, finally, come

forward with the truth of what happened that evening.

In 1980, Marine Addis and fellow commandos took a small steamer from

Port Stanley to the remote North Arm community on East Falkland.

They knew that a ceilidh was to take place and, in those pre-war days

in the Falklands, this was a big night out.

He was one of a party of six commandos training local volunteers to

protect the islands from invasion but their tour of duty was about to

end and they were out for a good time.

There is no doubt that a lot of drink was taken that evening. Most

seemed to have a good time. However, on the journey back to Stanley, it

was noticed that Marine Addis was not on board.

An inquiry was conducted by the local police force -- which at that

time consisted of one man, trained by Devon and Cornwall Police, and one

other.

The initial report suggested Marine Addis must have died in an

accident. However, his body was not recovered.

Mrs Ann Addis, mother of the marine, who is now presumed dead, was not

prepared to let the matter rest and has been campaigning for the

investigation to be re-opened.

As a consequence, the Royal Falkland Island Police, now a force of 17,

did re-open its files and sent a report to the Devon and Cornwall

constabulary -- which has trained the officers who have moved to the

island since the war with Argentina -- and new lines of inquiry were

opened.

In all, more than 50 people were interviewed in the UK. They include

former Marines and one-time residents of the Falklands who had returned

to Britain.

Never at any stage has it been suggested the colleagues of Marine

Addis may have been involved in what is now, clearly, a murder inquiry.

Police suspect residents know more than they have been prepared to say.

As a consequence, Detective Chief Inspector Bob Pennington and

Detective Sergeant Steve Turpin are to continue the inquiry. They will

be followed shortly by two constables who will, via satellite, be able

to link with the Home Office's major incident computer system.

While they are following a cold trail, it was made clear last night

that fresh information had opened up new leads.

A spokesman said: ''We are hopeful that this will lead to a definite

conclusion. At the very least, we would hope to recover Alan's body,

which would bring some comfort to his mother.''

Prior to the detectives visit, Mrs Addis made an emotional plea on

video, urging those who might throw light on her son's death to come

forward.