LONDON, (Reuters) - Thousands of West Indians have migrated to Britain in the past century but Sam King is one of only a handful to have done it twice.

A farmer's son from Jamaica, King joined the Royal Air Force in 1943 and sailed to Britain on an Atlantic convoy to serve in World War Two and start a new life in Europe.

At the end of the war, however, the British sent him back to his homeland. Undeterred, he bought a one-way ticket to England and arrived in 1948 aboard the Empire Windrush on a voyage which has come to symbolise the start of the great post-war wave of Caribbean immigration to Britain.

He rejoined the Air Force and served for four years at a time when black people were a novelty in Britain and suffered regular discrimination and abuse. He bought a house in London in the 1950s and was soon joined by thousands of fellow Jamaicans.

``Having got the house, every year one of my relatives was coming,'' he says in a thick Caribbean accent, peppered with slang and undiluted by more than half a century in Britain.

``They in turn multiplied this all over...The immigration to England started.''

King's recollections, recorded by a historian for the Museum of London, are among 150,000 items, collected from 30 museums and libraries, which can be accessed through a major interactive Web site launched on July 30.

The site, www.movinghere.org.uk, is run by Britain's National Archives and aims to shed light on the often forgotten stories of thousands of immigrants and refugees -- Caribbean, Irish, Jewish, Indian, Pakistani and Bangladeshi -- who have settled in Britain in the past 200 years.

SLAVES, CRICKETERS AND PATIENTS
The site allows visitors to see rare photographs from 1869 of emaciated black slaves in the hold of a ship, and pictures of Fay Sislin, Britain's first black woman police officer.

There is a Victorian portrait of Kumar Shri Ranjitsinhji, who arrived from Gujarat in 1880 and became the first Indian to play county cricket in England. He went on to captain England and played in 15 test matches between 1896 and 1902.

Visitors can listen to an interview with second-generation Jewish immigrant Keith Rogers who, in 1932, became the first person in London to be treated with penicillin by the man who developed the groundbreaking antibiotic, Alexander Fleming.

There is a copy of a booklet offering ``useful information and friendly guidance'' to Jewish refugees from Nazi Germany. It warns them not to speak German and not to ``make yourself conspicuous by speaking loudly, nor by your manner or dress.''

Also on the site are Home Office files relating to Irish playwright Brendan Behan, who was expelled to Ireland after spending two years in a British juvenile prison for trying to smuggle explosives into Britain at the age of 16.

Irish Republican guerrillas were planning to use the explosives for a bombing campaign.

Behan applied from Ireland for permission to return to Britain in the 1940s but the Home Office was unsympathetic.

``Behan appears to be a thoroughly bad type,'' reads a Home Office letter from 1948. ``He is not a person to be trusted.''

SHAKING OFF THE ``DUSTY AND MUSTY'' IMAGE
The architects of the Web site say it will help Britons find out more about their melting-pot nation.

``For the first time, all this material has been digitised so that you can see it in your living room,'' said Sarah Tyacke, chief executive of the National Archives. ``Archives are moving away from their dusty and musty image by making these documents available at the click of a mouse.''

The site is not just about the past.

Contributors say they want it to inform the current debate about immigration to Britain, which has tended to degenerate into an ugly row about the rights of asylum seekers and refugees to stay in the country.