Thomas Stevenson Colvin (Tom), Church of Scotland missionary in Malawi and Ghana, was born in Glasgow on 16 April 1925. He attended the Royal Technical College, Glasgow (now Strathclyde University) where he was chairman of the Student Christian Movement and from where he graduated B.Sc. in 1945. After a period with the Royal Engineers in Burma and Singapore, Colvin returned to Scotland in 1948 to become student assistant minister at Fallin Parish Church in Stirling. Later in the same year he began a three year course in divinity at Trinity College, Glasgow, was again an active member of student bodies, and held the post of president of the SCM. He spent a year after leaving Glasgow as the Travelling Secretary of the SCM, then between 1952 and 1954 was Youth Secretary of the Iona Community.

In 1954 Colvin was ordained as a minister and appointed a missionary to Malawi (Nyasaland) where he was headmaster of Henry Henderson Institute, associate minister of Blantyre church and education secretary of Blantyre Synod. On the integration of Blantyre mission into the Synod in 1958 Colvin was appointed General Secretary but was unable to take up the post as the Welensky government declared him a prohibited immigrant. Colvin and his wife Patricia (Patsy, née McGregor), whom he had married in 1955, were forced to leave Malawi. In 1959 they went to Ghana with the Church of Scotland where Colvin was district pastor at Tamale, Northern Ghana. In Ghana Colvin was noted for his pioneering ecumenical programme of community development which he saw as a complement to evangelistic outreach and he was Organising Secretary of the Christian Service Committee of Northern Ghana.

In 1964 the Colvins were recalled to Malawi and Tom Colvin became development adviser to the Synod, being responsible for programmes to develop lay and clerical leadership training and directing the formation and growth of the Christian Service Committee. The CSC in Malawi, which from 1968 included the Roman Catholic church, was an attempt to encourage community development by Christians and to involve them in all levels of society and social planning and aid, in co-operation with secular bodies. Colvin was also involved in MEND (the movement of ecumenical action in national development), held the post of Secretary of the Christian Council of Malawi (1965-1967), and undertook many pastoral duties such as the chaplaincy of the University of Malawi. In 1974 the Colvins retired from Malawi but during 1975 Colvin made several return trips to Africa on a survey for the All Africa Conference.

From 1976 to 1984 he was warden and leader of ministry at Sydenham United Free Church in south-east London and particularly involved in urban community development. His experience and skills meant that he was frequently called on to give advice about the church in Africa and in 1984 he was appointed by the World Council of Churches and seconded to the Zimbabwe Christian Council as development consultant. The Colvins returned to Malawi with the Church of Scotland for three years in 1987 and, despite retiring in 1990, Colvin continued to advise on development projects throughout Africa and spent short periods in various countries. He revisited Malawi several times in the 1990s to advise on policy making and provide training for church leaders involved in relief and development. Colvin's promotion of the role of the church in development was not restricted to writing reports or organising committees. He was involved in many practical projects, organising relief for victims of famine and refugees and initiating various building, agriculture and health projects in villages and urban communities. Colvin was also noted for his interest in African music and hymns. He was concerned with helping the African church to use their own musical heritage in worship and to write hymns arising from the African context.

His publications on Africa include several books of hymns as well as books on the mission and church in Africa. Colvin died in Edinburgh on 24 February 2000.