David Cameron was Leader of the Conservative Party and Leader of the Opposition from his election as Leader on 6 December 2005 until he became Prime Minister on 11 May 2010. His tenure as opposition leader was characterised by opposition to the Great Recession from 2007 to 2009, and his relative youth and inexperience before becoming leader invited satirical comparison with Tony Blair. Cameron sought to rebrand the Conservatives, embracing an increasingly socially liberal position, and introducing the "A-List" to increase the number of female and minority ethnic Conservative MPs.

The Leader of His Majesty's Most Loyal Opposition, more commonly referred to as the Leader of the Opposition, is the person who leads the Official Opposition in the United Kingdom. The position is seen as the shadow head of government of the United Kingdom and thus the shadow prime minister of the United Kingdom.