Yorke was returned for the family seat at Reigate while under age, and transferred to Cambridgeshire at the next general election. Of a reserved disposition and in poor health, his main pleasure was in literature. He was a member of several learned societies, and a trustee of the British Museum—‘a bookish man, conversant only with parsons’, was Horace Walpole’s assessment.
Royston’s chief concern was to maintain the dignity of his family and to secure the lord chancellorship for his brother Charles. When Newcastle resigned in May 1762 Royston was anxious that his brothers should stay in office. To Charles he wrote, 27 Oct.:
The following month old Lord Hardwicke died. ‘We are all at sea without a pilot or rudder’, wrote the new head of the family.
He died 16 May 1790.
