Arthur Balfour
11 July 1902 5 December 1905 Conservative
Sir Henry Campbell-Bannerman
5 December 1905 3 April 1908 Liberal
H. H. Asquith
5 April 1908 5 December 1916 Liberal
David Lloyd George
6 December 1916 19 October 1922 Liberal
Andrew Bonar Law
23 October 1922 20 May 1923 Conservative
Stanley Baldwin
(1st term) 23 May 1923 16 January 1924 Conservative.
Ramsay MacDonald
(1st term) 22 January 1924 4 November 1924 Labour
Stanley Baldwin
(2nd term) 4 November 1924 5 June 1929 Conservative
Ramsay MacDonald
(2nd term) 5 June 1929 24 August 1931 Labour
Ramsay MacDonald
(3rd term) 24 August 1931 7 June 1935 National Labour
Stanley Baldwin
(3rd term) 7 June 1935 28 May 1937 Conservative
Neville Chamberlain
28 May 1937 10 May 1940 Conservative
Winston Churchill
(1st term) 10 May 1940 27 July 1945 Conservative
Winston Churchill
(2nd term) 26 October 1951 7 April 1955 Conservative
Sir Anthony Eden
7 April 1955 9 January 1957 Conservative
Harold Macmillan
11 January 1957 19 October 1963 Conservative
Harold Wilson
(1st term) 16 October 1964 19 June 1970 Labour
Edward Heath
19 June 1970 4 March 1974 Conservative
Harold Wilson
(2nd term) 4 March 1974 5 April 1976 Labour
James Callaghan
5 April 1976 4 May 1979 Labour
Margaret Thatcher
4 May 1979 28 November 1990 Conservative
John Major
28 November 1990 2 May 1997 Conservative
Tony Blair
2 May 1997 incumbent New Labour