 Having already become Dean of St Paul's (he was instituted to the Portpoole prebend by Robert Lowth, Bishop of London on 21 February 1787), his election was confirmed by John Moore, Archbishop of Canterbury, at St Mary-le-Bow on 10 March 1787 and he was consecrated a bishop by Moore (assisted by William Ashburnham, Bishop of Chichester; Shute Barrington, Bishop of Salisbury and Beilby Porteus, Bishop of Chester) at Lambeth Palace chapel on 11 March 1787.Pretyman maintained on close terms with Pitt, though Lincoln duties kept him from frequent visits to London, and shared Whig attitudes.In a sermon to the House of Lords on 30 January 1789, Pretyman condemned Charles I, executed by parliament in 1649, and praised his political opponents.