Yorke was more interested in agricultural and antiquarian pursuits than in Parliament. In 1792 he was returned for Grantham by his brother-in-law, on the united Brownlow and Rutland interest, as a seat-warmer until his son Simon came of age. He supported Pitt’s administration, ‘although constitutional diffidence would not allow him to speak in the House’. He was, however, admired as a conversationalist. No vote of his is known in this period. After his retirement, he published at his own expense works on Welsh genealogy. His income was £7,000 p.a., ‘every shilling of which he did spend’. ‘Nimrod’ remembered him as ‘the worst horseman I ever saw in a saddle’. His letters to the 3rd Earl of Hardwicke, his second cousin, suggest that he was something of a valetudinarian.
After suffering ‘with spasms on his chest’, he died 19 Feb. 1804,