The Shadow Chancellor of the Exchequer in the British Parliamentary system is the member of the Shadow Cabinet who is responsible for shadowing the Chancellor of the Exchequer. The title is given at the gift of the Leader of the Opposition and has no formal constitutional role, but is generally considered the second-most senior position on the opposition frontbench, after the Leader. Past Shadow Chancellors include Harold Wilson, James Callaghan, Edward Heath, Geoffrey Howe, Kenneth Clarke, Gordon Brown, and John McDonnell.

The Official Opposition Shadow Cabinet, or His Majesty’s Most Loyal Opposition Shadow Cabinet, but usually simply the Shadow Cabinet, is the committee of senior members of the Official Opposition who scrutinise the work of the Cabinet of the United Kingdom. Each Shadow Cabinet member is typically given a position which corresponds to that of a government minister in Cabinet. Shadow Cabinet members, known as Shadow Ministers, are usually appointed by the Leader of the Opposition. The roles of Shadow Ministers are to develop alternative policies, hold the government to account for its actions and responses, and act as spokespeople for the opposition party in their own specific policy areas. By convention, Shadow Ministers are drawn either from serving members of the House of Commons or the House of Lords, with most chosen from the former. Since May 2010, Labour has been the Official Opposition, and its leadership therefore forms the current Shadow Cabinet.