Indeed, I may have posted a too difficult topic... because many likely candidates are too young, too old, died, too much in "action", etc to be picked when you want...
Gaitskell, Butler, Castle, Whitelaw, Jenkins, Patten, Heseltine, etc (even Mountbatten !) would all have made interesting presidents. But that doesn't match.
So, one line may be this one:
(just remember the first elections took place in December from 1945 to 1960, but in February from 1965 on, because of Churchill's death... that's important in 1970 and 1990, of course...)
1945-1950: Arthur Greenwood
1950-1955: Stafford Cripps
1955-1965: Winston Churchill
1965-1970: George Isaacs
1970-1975: Michael Stewart
1975-1980: Lord Gerald Gardiner
1980-1985: Harold McMillan
1985-1995: Lord Peter Carrington
1995-2000: Sir Geoffrey Howe
2000-2005: Neil Kinnock
2005-...: Jack Straw
I thought there are no more Sirs and Lords anymore
Anyway, good list