Probably while at the papal curia, he was consecrated at some point between 7 and 10 June 1331.[3] The Chronicles of Mann states that Thomas de Rossy "was the first to exact from the churches of Mann twenty shillings for visitation dues", and that "he was also the first who exacted from the parochialrectors the tithes received by them from strangers engaged in the herring fishery".[4] His surname is known from a papal record dating to 1346, a record concerning the future of a benefice Thomas held before he was promoted to episcopal status.[5]
According to the Chronicle, after an episcopate of eighteen years, he died on 20 September 1348 and was buried at Scone.[6]
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 Scoticanae 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.