Llewellin was educated at Clifton College, Bristol“Who was Who” 1897-2007 London, A & C Black, 1991 and Fitzwilliam College, Cambridge. He was made a deacon at Michaelmas 1964 (20 September) and ordained priest the Michaelmas following (19 September 1965) — both times by Michael Gresford Jones, Bishop of St Albans, at St Albans Cathedral; and was a curate at Radlett. After serving a second curacy at Johannesburg Cathedral, and being expelled from South Africa by the apartheid Nationalist government of the day in 1971, he was then successively the Vicar of Waltham Cross, the Rector of HarpendenCrockford's clerical directory, London, Church House 1995 and a canon of Truro Cathedral and ordained to the episcopate as the suffragan Bishop of St Germans (1985–92). He was consecrated a bishop by Robert Runcie, Archbishop of Canterbury, on All Saints' Day 1985 (1 November) at Westminster Abbey.
