Patrick was educated at the University of St. Andrews, where he was dean of the Faculty of Arts in 1457. His royal descent and connections through his mother's marriages with the powerful family of Angus and with the good Bishop Kennedy, his uterine brother, pointed to the service of the church as the road to high preferment, and in 1463 he was consecrated Bishop of Brechin. Three years later he succeeded Kennedy, who died in July 1465, in the primacy of Scotland. Soon after his succession to St. Andrews, Graham went to Rome to avoid the enmity of the Boyds, then at the height of their power in the Scottish court, and to procure his confirmation by the pope, and he remained abroad till the fall of the Boyds in 1469. He was present as conservator in a provincial council held in Scotland in July 1470, by which an end was put to the dispute between John Lochy, the rector of the university of St. Andrews, and the college of St. Salvator, on which Pius II had conferred the power of granting degrees in theology and arts. The rector resisted, but Graham obtained its recognition. He returned to Rome on the accession of Sixtus IV, and at his instance a series of bulls were issued by that pope in the first year of his pontificate, which raised St. Andrews to the dignity of an archbishopric and made the Scottish bishops subject to its see. These bulls are dated 17 Aug. 1472.
From then until his death Patrick felt the wrath of the other Scottish bishops, who resented being under the governance of one of their own as Archbishop. He was finally driven from his position through the machinations of those against him and his own King, and spent his final years in prison. First he was kept in Inchcolm, then for fear of his release by the English fleet in Dunfermline, he was moved to the castle of Lochleven, where he died in 1478. He was buried in the chapel on the island of St. Serf.
Source www.thepeerage.com from The Dictionary of National Biography, Oxford Univ. Press
http://onlinebooks.library.upenn.edu/webbin/metabook?id=dnb