While earning a university degree between 1409 and 1417, Bullock gained several benefices in Scotland, and claimed the headship of St Andrews Cathedral Priory before becoming Bishop of Ross in 1418.
Though his career has not been elaborated by modern historians, Bullock is known to have been a university graduate, having a B. Dec., i.e. a Bachelorate in Decrees (canon law); he did not hold that degree in 1409, but did by 1417.
[6] The pope has reserved the bishopric of Ross for his own appointment and, on 16 March, Thomas Lyell, who had been elected by the cathedral chapter of Fortrose "in ignorance of the reservation", was granted 40 crowns in compensation for his expenses, and two days later, he was granted a canonry in the diocese of Aberdeen allowed to be held alongside his other benefices.
[8] He was consecrated between 16 July, when as "elect and confirmed" he sent a proctor to the Provincial Synod, and 16 August 1420, when he as "through the grace of Gode Byschop of Rosse", sealed a charter.
[11] He is dead by 26 September 1440, when a papal mandate rejected the postulation of Andrew Munro and provided Thomas de Tulloch to the bishopric, explicitly vacant because of Bullock's death.