He became involved in politics in 1742, beginning with his election as a Member of Parliament for Boroughbridge, now in North Yorkshire, and appointment as Solicitor General. In the absence of a strong Attorney General, he became the main spokesman for the government in the House of Commons, and was noted for his "great powers of eloquence" and described as "beyond comparison the best speaker" in the House of Commons. With the promotion of Sir Dudley Ryder to Lord Chief Justice in 1754, he became Attorney General, and when Ryder unexpectedly died several months later, he took his place as Chief Justice.