His father would be ennobled in 1715 as Baron Hamilton of StackAllan and advanced to Viscount Boyne in 1717.
[2][3][4] Gustavus's mother was the eldest daughter of Sir Henry Brooke by his second wife, Anne St George.
Brooke was knight of Brookeborough, County Fermanagh, and governor of Donegal Castle.
[7] That parliament lasted from 12 November 1715 to 11 June 1727 when it was dissolved by the king's death.
Hamilton was reelected to one of the two seats for County Donegal in the general election of 1727, which was held for the only Irish Parliament of King George II, which lasted from 14 November 1727 to 25 October 1760.