[1] Educated at Reading grammar school, Jemmat went to Magdalen College, Oxford in 1610, and graduated B.A.
[3] By appointment of the House of Commons, Jemmat in 1642–3 was lecturer at Dunstable and Kingston upon Thames, and in the neighbourhood of Faversham.
[2][3] Jemmat became vicar of St Giles's, Reading, by grant of the House of Lords under the great seal, 20 December 1648; the former vicar, Jemmat's elder brother John, had been buried in the church on 10 December 1648.
He died at Reading on 28 Jan 1678, and was buried in the chancel of St Giles's Church on 31 January.
[1] On 11 October 1619 Jemmat married Anne Pocock at St Giles's Church, Reading.