In 1994, concluding a process that began five years earlier with the desegregation of public facilities, the unbanning of the ANC and Nelson Mandela's release from prison, South Africa held its first non-racial elections. Mandela became presidentat the head of a government of national unity, the last remaining international sanctions were lifted, and the country took up its seat again at the UN General Assembly after an absence of 20 years. It was a time for rejoicing but also, for anti-apartheid campaigners around the world and not least in Britain, the end of a journey.

"We had accomplished what we set out to do," says Christabel Gurney, who joined the British Anti-Apartheid Movement (AAM) in 1969 and edited its monthly newsletter throughout the 1970s. AAM was dissolved and some of its members founded a new, smaller group, ACTSA, which still campaigns for justice and rights in southern Africa, combating the legacy of apartheid. One of AAM's final acts was to set up a committee to preserve and catalogue the great mass of historical material – documents, posters, leaflets, speeches, video and photographs – recording more than three decades of campaigning.

With the help of the Bodleian Library in Oxford, where the archive is stored, and money from the Heritage Lottery Fund and the Amiel and Melburn Trust, that goal too has now been accomplished. An engrossing new website, Forward to Freedom: the History of the British Anti-Apartheid Movement 1959-1994, went live this week, featuring archive highlights such as iconic posters from campaigns against the death penalty for the Rivonia accused and the 1970 Springbok cricket tour, footage from the Nelson Mandela tribute concert at Wembley Stadium in 1988, and and letters from Margaret Thatcher arguing against sanctions on South Africa.

The site also includes interviews with more than 50 anti-apartheid activists, including the Specials' Jerry Dammers (author of protest song Free Nelson Mandela), actor Louis Mahoney, trade unionists Jack Jones and Ron Todd, the politician David Steel, who was AAM president in the 1960s, churchman David Haslam and journalists such as the Guardian's Victoria Brittain, as well as grassroots campaigners such as the students who called for university disinvestment. A related pop-up exhibition makes its debut at the House of Commons in June, and an educational pack is being prepared for secondary schools.

Britain's biggest ever pressure group on an international issue, AAM remains "a sort of case study of what can be done when a group of people, working initially in pretty hopeless circumstances – because early on, there was a great deal of hostility – can just build things up, by lots of small gestures, and have an effect," says Gurney. "I hope this will interest a new generation in what was achieved. I think there are lots of places and situations in the world now, which may not be quite as straightforwardin a way, but where small things that don't seem very successful for a long time … can build up and achieve something."