British Political Realignments

[adma]

I would argue 1997 is a realignment.  Post-1997 there was and still is a structural advantage of Labour Party where it can capture a majority of seats with a smaller vote share relative to the Tories.  

Though the ghost of said "structural advantage" was evident in 1983--after all, longest-suicide-note and all, Labour still won 209 seats in 1983 vs the Tories' 165 in 1997...

[ChrisDR68]

You could argue that there was a realignment as soon as Michael Foot was elected Labour leader in 1980. His election over Healey helped to provoke the Gang Of Four to leave the party and form the SDP.

If Denis Healey wins the leadership David Owen and Shirley Williams may well have stayed in the party (although that is by no means certain) and the general election of 1983 or 1984 becomes much more competitive overnight.

With Owen and Williams within the party, Healey's succession would likely have been between either of those two figures and Neil Kinnock later on in the 1980's.

Of course there would still have been the usual left / right conflict within the Labour Party but I doubt it would have been as bad as it in fact turned out to be during the 1980's.