Wagstaffe was born in Cublington, Buckinghamshire, UK, The only son of the town's rector, and related to the Wagstaffe family of Knightcote, Warwickshire.
He was educated at a school in Northampton, entered Lincoln College, Oxford in 1701, and graduated B.A.
The same year, he joined the London "practice of physics" of his relative Thomas Wagstaffe.
He became a fellow of the Royal College of Physicians on 22 December 1718, and was a censor in 1720.
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