Gregory is found as a papal judge-delegate in 1219, 1224 and 1225.[3] He was present at the royal council in Forfar in 1225, and at Dundee in 1230.[3]
He appears in another Arbroath document dating to 1242, his last appearance in contemporary sources.[4]
During Gregory's time the cathedral was run by Scottish priests called Céli Dé, governed until at least the early part of Gregory's episcopate by a prior named Máel Brigte (Mac Léoit, "MacLoud").[5] The old abbots of Brechin were in the process of becoming the secular Mac in Aba (filius Abbe, "MacNab") lords of Glen Esk.[6] Soon after Gregory's death these priests "by change of name" came to be "styled as canons".[7] Gregory may have been responsible for this nominal change.[8]
Gregory died sometime between his last appearance in 1242, and 1246 when the papacy mandated the confirmation of his successor Albin.[9]
Barrow, G. W. S. (1992), "The Lost Gàidhealtachd", in Barrow, G. W. S. (ed.), Scotland and its Neighbours in the Middle Ages, London: The Hambledon Press, pp. 105–26, ISBN1-85285-052-3
Dowden, John (1912), Thomson, John Maitland (ed.), The Bishops of Scotland : Being Notes on the Lives of All the Bishops, under Each of the Sees, Prior to the Reformation, Glasgow: James Maclehose and Sons
Watt, D. E. R.; Murray, A. L., eds. (2003), Fasti Ecclesiae Scotinanae Medii Aevi ad annum 1638, The Scottish Record Society, New Series, Volume 25 (Revised ed.), Edinburgh: The Scottish Record Society, ISBN0-902054-19-8, ISSN0143-9448