Philippe de Carteret was born at Trinity Manor on 22 January 1733 the youngest son of Charles de Carteret, Seigneur of Trinity and Francoise Marie St Paul. As a youngster he developed a great love for the sea. In 1747 Philip entered the Navy as servant to Captain George Edgecumbe. He served as a midshipman on a number of ships before taking his lieutenant's exams in late 1755. He received his commission as Lieutenant in 1757 aged 24 years. This was a relatively old age to achieve such rank in the navy probably due to the fact that he had not served in a major theatre of war. In 1761 on the death of his elder brother he inherited Trinity Manor from his father. His sister, Anne, ran the estate while he was at sea.