Archbishop Desmond Tutu has dedicated a stained glass window to the late anti-apartheid activist, Bishop Trevor Huddleston, at his former school.
Bishop Trevor Huddleston died in West Yorkshire in 1998
The memorial is located in the chapel of Lancing College, West Sussex.
Bishop Huddleston studied there between 1927 and 1931, describing it as "a place that allowed me to grow very much to be what I wanted to be".
He died in 1998 at the age of 84 after campaigning against apartheid in South Africa for much of his life.
Speaking at a dedication service at the college on Tuesday, Archbishop Tutu said: "If you could say that anybody single-handedly made apartheid a world issue, then that person was Trevor Huddleston."
Bishop Huddleston, who was an Anglican priest, went to South Africa in 1941, where his work led to him ultimately becoming president of the Anti-Apartheid Movement.
He was a friend of Archbishop Tutu for more than 50 years.
The Huddleston Memorial Window features the roofs of a shanty town and a depiction of the bishop himself.
It was created by Chichester-based artist Mel Howse, a member of the British Society of Master Glass Painters.
Tuesday's service was also attended by members of the Huddleston family, other anti-apartheid campaigners and senior school and church representatives.
The ceremony also saw the announcement of Lancing College's new Trevor Huddleston Scholarship, a free two-year Sixth Form placement for a pupil from south London.