In 1710 he took the name of Long on inheriting the estate of Whaddon in Wiltshire from his great-uncle Sir Walter Long. The original Coat of Long was, through some error, allowed to him by the College of Arms. He successfully stood for parliament in the 1715 general election being returned as Member of Parliament (MP) for Harwich. He held the seat until 1734.
In 1740 he founded the Erwarton Almshouses close to his home in Erwarton.
On 11 July 1715 Parker married in London, Martha East and they had four daughters:
- Martha (1716–1775) married John Thynne Howe, 2nd Baron Chedworth
- Elizabeth (1717–1757)
- Katherine (b. 1719)
- Dyonisia (b. 1722)
On 20 January 1741, John Perceval, 1st Earl of Egmont wrote in his diary:
"This morning died my brother-in-law Sir Philip Parker, at 3 o'clock, choked by one of those fits he has had for 12 weeks past at sundry times."
- "PARKER, Sir Philip, 3rd Bt. (1682–1741), of Erwarton, Suff". History of Parliament Online. Retrieved 15 August 2018.