Stephen Poyntz was educated at Eton College, a king's scholar and in 1702 captain of Montem.
He acted as Townshend's confidential secretary, communicating on his behalf with the English ambassadors abroad, and, through his chief's influence, he moved into the diplomatic service.
He obtained the French agreement to dismantle the fortifications at Dunkirk, regarded as a deft diplomatic coup as well as a political triumph for the Whigs in London.
About 1735 he purchased from the Hillersdon family an estate at Midgham in the parish of Thatcham, near Newbury, Berkshire; the Duke spent some of his early years there.
It was in his rooms at St James's Palace that Charles Mordaunt, 3rd Earl of Peterborough, in 1735 acknowledged that Anastasia Robinson was his wife.
She served as a maid of honour to Queen Caroline of Ansbach and had been a great beauty, addressed by Samuel Croxall in his poem The Fair Circassian.
Louisa died unmarried and Sophia married Sir Roger Martin, 3rd Baronet of Long Melford.
Mrs. Poyntz was in great favour at Versailles in August 1763, when she cured Madame Victoire of the stone.
[11] Poyntz was a friend of Samuel Richardson the novelist, a patron of James Ferguson the astronomer, and helped the scholar Elizabeth Elstob by a recommendation of support to the Queen.