Thomas Rundle was the son of an Exeter clergyman. He attended grammar school in Exeter and then Exeter College, Oxford where he met Edward Talbot (1693-1720), younger son of William Talbot (1659-1720), Bishop of Salisbury. Through the patronage of the Talbot family Rundle was appointed to a succession of offices culminating in his appointment to the see of Gloucester in 1733. Opposition within certain factions of the church led the post being given to Martin Benson and Rundle's appointment to the see of Derry. Rundle greatly enjoyed his life in Ireland, building himself a house Dublin and winning the affection of the local clergy. He died unmarried and left much of his fortune to John Talbot (d.1749), nephew of his great friend Edward Talbot.