After the Act of Union he sat as a Whig[2] in the House of Commons of the United Kingdom of Great Britain and Ireland.
Elliot was elected to the Irish House of Commons in 1796 as a Member of Parliament for St Canice.
[3] He held that seat until the Parliament of Ireland was abolished at the end of 1800 by the Act of Union,[3] when he did not initially have a seat in the new Parliament of the United Kingdom.
However, he was elected at an unopposed by-election[4] in March 1801 as MP for Portarlington, and held that seat until the 1802 general election,[5] when he was returned to the House of Commons of the United Kingdom for the English borough of Peterborough.
[1] He was sworn as a Privy Councillor in March 1806, in Dublin Castle,[6] and appointed on 28 March as Chief Secretary for Ireland[6] in the Ministry of All the Talents.