Somerville was born in the
Dunedin suburb of
Andersons Bay in 1910, the son of Grace Isabella (née Isherwood) and James Cleland Hall Somerville. He attended the
University of Otago, graduating with a Master of Arts degree with second class honours in 1935. From 1935 to 1937 he trained at the Theological Hall of the Presbyterian Church of New Zealand at
Knox College, at the end of which time he received his certificate of license. He then travelled to the United Kingdom, where he studied at
Westminster College, Cambridge and the
University of St Andrews. He returned to New Zealand in 1938 to become the minister at
Tapanui. After the war, he returned to Tapanui, and then moved to the
Wellington parish of St Andrew's-on-the-Terrace, where he served from 1947 to 1963. Somerville was
Moderator of the General Assembly of New Zealand in 1960–61. Returning to his home town of Dunedin, Somerville was Master of Knox College from 1964 to 1978. He died in Dunedin on 5 October 1999 and his ashes were buried in
Andersons Bay Cemetery with those of his parents. A commemorative bench outside the chapel on
Quarantine Island with the inscription, 'Psalm 139 v 9-10,' was placed by his family. ==Honours==