What if the SDP-Liberal Alliance wins the 1983 UK election.
I know this is quite a bit ASB considering how hard the FPTP is on 3rd parties. Perhaps if Tony Benn was elected as Labour leader in the early 80's and the UK had lost the Falklands War is could happen. Once the Labour vote dropped below a certain point and a few more Tories defected to the Alliance the FPTP system would actually work in favour of the Alliance.
Regardless however how would the UK be different if the Alliance had won?
By the way, Labour only got around 27% of the national vote in 83 but due to the electoral system still got a relatively high proportion of seats. Of course it all depends on the distribution of votes in key seats, but out of interest, what would be the percentage of national vote below which the Labour Party would have lost a LARGE numbers of seats. Assuming for simplicity's sake the drop is relatively even throughout the nation?