Ridley is best known for his writings on science, the environment, and economics. Since 2013, he has been a Conservative hereditary peer, with a seat in the House of Lords. Ridley was chairman of the UK bank Northern Rock from 2004 to 2007, during which period Northern Rock experienced the first run on a British bank in 150 years. Ridley resigned and the bank was bailed out by the UK government leading to the nationalisation of Northern Rock.