[1] Castlemaine was a Member of the Irish House of Commons for Athlone from May 1800 until the Act of Union in 1801, alongside his elder brother, William.
[2][3] In 1839 he succeeded his elder brother as second Baron Castlemaine according to a special remainder in the letters patent.
Lord Castlemaine married Anne, daughter of Arthur French, in 1790.
He died after a long illness in April 1840, aged 72, and was succeeded in the barony by his eldest son, Richard.
His daughter Sarah married Major General Christopher Hamilton CB.