Philipps was returned to parliament for Pembrokeshire in 1765 (succeeding his deceased father), and held the seat at the 1768 general election.
[2] At the 1806 General Election, Philipps was opposed by the Owen family of Orielton but successfully held the seat.
At the ensuing election, however, Campbell was opposed and defeated by Sir John Owen of Orielton, who had recently inherited that estate from a distant cousin.
His only son with his first wife, Mary Grant, John Philipps, was taken for dead after the Battle of Trafalgar.
He bequeathed his estates, including the family seat of Picton Castle, to his cousin Richard Grant, who assumed the surname of Philipps.