Michael Tregury was born in the parish of St Wenn in Cornwall. He was educated at the University of Oxford, and was at some time Fellow of Exeter College, Oxford. He was consecrated in St. Patrick's church and was Archbishop of Dublin from 1450 to 1471
In 1451 more than fifty people from his diocese went to Rome to celebrate the jubilee then promulgated by Pope Nicholas V. Those who returned safe in 1453, brought the sad news that Constantinople was taken by the Turks, and the Emperor Palaiologos slain. The Archbishop Michael was so afflicted at the news that he proclaimed a fast to be observed strictly throughout his diocese for three successive days, and granted indulgences to those who observed it, he himself walking in procession before his clergy to Christ church and clothed in sackcloth and ashes.
In 1453 he was taken prisoner in the bay by pirates, who were carrying off some ships from the harbor of Dublin. They were pursued to Ardglass, in County Down; five hundred and twenty of them were slain and the prelate released.
Having presided over his see for twenty years, he died on the 21st of December, 1471, at a very advanced age, in the manor-house of Tallagh, which he had previously repaired. His remains were conveyed to Dublin attended by the clergy and citizens, and were buried in St. Patrick's cathedral.
He was buried in Dublin and his epitaph reads..
Preasul Metropolis Michael hic Dublinenuswhich translates as
Marmore tumbatus, pro me Christum flagitetis
Here's Michael the Prelate of Dublin See,
In Marble intomb'd, invoke Christ for me..