Christopher Paget Mayhew, Baron Mayhew (June 12, 1915—January 7, 1997) was a British politician who was a Labour Member of Parliament from 1945-1950 and from 1951-1974, when he left the Labour Party to become a Liberal. In 1981, Mayhew recieved a life peerage and was raised to the House of Lords as Baron Mayhew.

Mayhew attended Haileybury and Christ Church, Oxford as an exhibitioner. While at Oxford, he became President of the Oxford Union. Mayhew served in the British Army during the Second World War, rising to the rank of Major.

Mayhew was elected to Parliament from the constiuency of Norfolk South in 1945. He became Under-Secretary of State at the Foreign Office where he served under Ernest Bevin and acquired the strong pro-Arab views that would make him a distinctive figure in British politics. Although Mayhew lost his seat in 1950, he soon returned to Parliament upon the death of Bevin, when he inherited Bevin's seat of Woolwich East .

During Labour's 13 years in opposition, Mayhew played an important role in presenting the Labour Party on television, both as a commentator on the BBC and as a presenter on Labour Party Political Broadcasts. He introduced the first Labour broadcast during the 1951 election in which he talked with Sir Hartley Shawcross. Mayhew also became known as one of the fiercest opponents of unilateral nuclear disarmament in the Labour Party. Mayhew also served as Shadow War Secretary from 1960-1961 and as an Opposition Foreign Affairs Spokesman from 1961-1964.

When Labour took office in 1964, Mayhew became Minister for the Navy . After the Wilson government decided to shift British airpower from carrier-based planes to land-based planes in 1966, Mayhew, along with the First Sea Lord, Sir David Luce , resigned.

Mayhew had been feeling increasingly uneasy with Labour policies under Harold Wilson and in 1974, he defected to the Liberals, being the first Member of Parliament to cross the floor to the Liberals in more than half a century. In the October 1974 election, Mayhew contested Bath, instead of Woolwich East in order not to split his constiuency party in Woolwich East. Mayhew lost Bath, which he also unsuccessfully contested in 1979. In 1981, Mayhew became a life peer and became the Liberal Spokesman on Defense in the House of Lords as well.

Mayhew also was active as an advocate for the mentally ill and served as Chairman of MIND (National Association for Mental Health ) from 1992-1997. Mayhew wrote several books, including his autobiography, Time To Explain, in 1987.

Although Christopher Mayhew's career never lived it up to its early promise, he did serve an important role in British political history. Mayhew's defection to the Liberals was to serve as the forewarning of the split within the Labour Party that would occur in 1981 with the rise of the SDP. Mayhew's defection was the first sign of the large rift growing between the Left and Right in the Labour Party and began the process by which the Liberals and political heirs, the SDP-Liberal Alliance and the Liberal Democrats became considered a major force in British politics.