By the time of his move to London in 1736, Hartley was known other campaigners of variolation, such as Hans Sloane and James Jurin, president of the Royal Society. He also had the support of important Whig families in Suffolk, notably of Charles Townshend, 2nd Viscount Townshend ('Turnip' Townshend). Hartley's daughter Mary wrote that "the old Lord Townshend (then Secretary of State) treated him with as much kindness as he had had been an additional son, and all the sons and daughters as an additional brother". He was inducted into the Royal Society, and he also became a physician to Thomas Pelham-Holles, 1st Duke of Newcastle, and his wife. In 1736 he offered to "recommend" John Byrom to George II.