You gave me an idea. It's kinda shit and I struggled to find an SDP analogy because this was mainly off the cuff, but hey ho;
1945-1952: Clement Attlee (Labour)
def. 1945: Winston Churchill (Conservative), Archibald Sinclair (Liberal), Ernest Brown (National Liberal)
def. 1950: Anthony Eden (Union), Clement Davies (Liberal)
1952-1957: Anthony Eden (Union)
def. 1952 (Minority): Clement Attlee (Labour), Clement Davies (Liberal)
def. 1952: Clement Attlee (Labour), Clement Davies (Liberal)
1957-1968: Jennie Lee (Labour)
def. 1957: Anthony Eden (Union), Jo Grimond (Liberal)
def. 1961: Peter Thorneycrot (Union), Jo Grimond (Liberal)
def. 1965: Iain Macleod (Union), Jo Grimond (Liberal)
1968-1975: Francis Noel-Baker (Labour)
def. 1970: Iain Macleod (Union), Richard Wainwright (Liberal)
1975-1985: Enoch Powell (Union)
def. 1975: Francis Noel-Baker (Labour), Richard Wainwright (Liberal)
Oh, you've reminded me to post this.
Leaders of the Conservative Party
1933-1946: Winston Churchill
1946-1950: Leo Amery
1950-1953: Waldron Smithers
1953-1962: David Price-White
1962-1964: Michael Noble
1964-1964: Florence Horsbrugh
1964-1977: Tony Barber
1977-1980: Hector Munro
1980-1980: Margaret Thatcher
1980-1985: Peter Morrison
1985-1985: Margaret Thatcher
1985-1986: John Peyton
1986-: Leon Brittan
Leaders of the Labour Party:
1933-1935: Charles Cripps
1935-1945: Hugh Dalton
1945-1960: Ellen Wilkinson
1960-1967: Alf Robens
1967-1971: Eric Varley
1971-1973: Eric Heffer
1973-1975: Bob Mellish
1975-1986: Chris Smith
1986-: Shirley Williams