He was the younger son of Sir Robert D'Amory, Knight, of Bucknell and Woodperry, Oxfordshire. Sir Roger also possessed in his own right the manors of Bletchington and Holton, Oxfordshire, Standon in Hertfordshire, Caythorpe in Lincolnshire, and Knaresborough and St. Briavels' Castles.
He was summoned to parliament on 20 November 1317, and in the 11th (1318), 12th (1319), 13th (1320) and 14th (1321) years of the reign of King Edward II, whereby he is held to have become Lord d'Amory.
He had been a favourite of King Edward II of England until he was displaced by Hugh Despenser the Younger. D'Amory took an active part in the Despenser War in 1321–1322 and was one of the principals in this affair. He captured Gloucester, burnt Bridgnorth, was at the siege of Tickhill and the battle at Burton-on-Trent. As a result, his lands were confiscated and orders were issued for his arrest. Retreating before the King's forces, being either sick or wounded he was left behind at Tutbury Castle, Staffordshire, where he was captured on 11 March 1322 (1321/1322). He was quickly tried and condemned to death. It appears, however, that his illness beat the executioner as he died there "of illness" two days later, and was buried at St. Mary's, Ware, Hertfordshire.
He married shortly before 3 May 1317 Elizabeth de Clare, being her third husband. They had one child:
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