The following information has been extracted from Newcourt's Repertorium and The History and Antiquities of the County of Buckingham Vol 3.
John Gray was instituted as Rector of St Botolph's, Bishopsgate on 13 November 1398. He resigned sometime before 23 October 1399, when he was succeeded as Rector of the benefice by Roger Malon.
John succeeded Thomas Thorpe as Rector of Thorley sometime after 4 June 1405, the date when his predecessor at St James the Great, John Berton, was instituted as Rector of St Mary's, Hitcham in Buckinghamshire. John remained at St James' until his death sometime before 2 September 1431, when he was succeeded as Rector of St James by William Seton.
It seems likely that the John Gray who was Rector of Thorley is the same John Gray who is recorded in a Lincoln Cathedral Register as having died in Thorley about the year 1435 and who was sometime rector of Tylly in the diocese of Bayeux in Normandy.
Philip Hargrave
February 2014