Lyell was one of very few lawyers to have combined a successful career in Parliament and a major private practice. He was also the longest continuously serving law officer for more than 100 years. After 20 years at the Bar he was appointed Solicitor-General from 1987 to 1992 under Margaret Thatcher, during which time he appeared in the Factortame case, and Attorney General for England and Wales and Northern Ireland under John Major from 1992 to 1997. He was knighted in 1987. He stood down as an MP at the 2001 election.