Sir Oliver Letwin is a British politician, Member of Parliament (MP) for West Dorset from 1997 to 2019. Letwin was elected as a member of the Conservative Party, but sat as an independent after having the whip removed in September 2019. He was Shadow Chancellor of the Exchequer under Michael Howard and Shadow Home Secretary under Iain Duncan Smith. He was Chancellor of the Duchy of Lancaster from 2014 to 2016.

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.