He was the most senior permanent official in the Dublin Castle administration between 1812 and 1830, during which time he opposed Catholic emancipation and the liberal agendas of several Lords Lieutenant of Ireland.
[1] After a period managing his father's estates at Coole Park in County Galway, in 1795 Gregory entered public service as surveyor of Skerries in the Irish administration of Lord Fitzwilliam.
Gregory succeeded to his father's extensive estates and property in 1810 and continued with minor roles in the Irish administration until 1812.
[1] The new Chief Secretary for Ireland, Sir Robert Peel, soon became accustomed to delegating important decisions to Gregory, who was recognised for both his ability and immaculate manners.
Under the early years of Lord Liverpool's premiership, Gregory's influence at Dublin Castle was supreme.
[1] Gregory was an uncompromising opponent of Catholic emancipation, which he regarded as a concession which would lead to the disintegration of the British Empire.