[4] When his father was made the Earl of Arran in 1762, he assumed the courtesy title of Viscount Sudley for himself.

[2][5] He was elected to the Irish House of Commons for Donegal Borough in 1759, a seat he held until 1761 and again from 1768 to 1774 and also represented County Wexford between 1761 and 1768.

In 1773, he succeeded his father as second Earl of Arran and entered the Irish House of Lords.

[2] He was admitted to the Irish Privy Council in 1771 and in 1783 he was invested as one of the original sixteen Knights of the Order of St Patrick.

Together, they had seven children:[2] Lord Arran died in October 1809, aged 75, and was succeeded in his titles by his eldest son Arthur.