In the early 1950s Canon John Collins established a Fund to combat racism in South Africa. This led to the inauguration of the Treason Trial Defence Fund in 1956 and then to the formation of the Defence and Aid Fund in the early 1960s.

These Funds collected money to support the families of those charged and imprisoned in South Africa for their opposition to apartheid, and to provide legal defence for those accused in political trials. When the Defence and Aid Fund was banned in South Africa in 1966, under the Suppression of Communism Act, the work was taken over totally by the International Defence and Aid Fund for Southern Africa (IDAF) in London.

IDAF included within its brief all countries in Southern Africa under white-minority or colonial rule. As these countries became independent IDAF ceased to include them in its brief. With the approach of negotiations for a non-racial constitution in South Africa, and the lifting of the South African ban against IDAF (in 1990), it was decided that the organisation should close during 1991 and that any further work should be carried out by organisations based in South Africa. The South African Legal Defence Fund (SALDEF), based in Cape Town, was the successor to IDAF.

Huddleston was Chairman of IDAF, 1983-1998.