Fooling around with www.electoralcalculus.uk, I got the following result for the 1983 general election:
Popular vote (inputted by me)
SDP/ Liberal Alliance 38%
Conservative 32.2%
Labour 26.6%
I increased the OTL Alliance vote by 12%, taking roughly 10% from the Tories and 2% from Labour.
Seats (calculated by Electoral Calculus)
Labour 213
Conservatives 207
Alliance 205
NI Unionists 12
SNP/ PC/ SDLP 9
DUP 3
I went through each constituency on Wikipedia to get the breakdown of returned Liberal MPs as opposed to returned SDP MPs, and calculated 112 Liberals and 93 SDP.
POD would be no Falklands War or the war somehow goes badly to the British, with unemployment as high as it was that would probably be enough but you can add other government misteps. Note that the Labour vote share is close enough to OTL that they really just need the Alliance as being seen as a more viable potential government.
So what happens next?
Popular vote (inputted by me)
SDP/ Liberal Alliance 38%
Conservative 32.2%
Labour 26.6%
I increased the OTL Alliance vote by 12%, taking roughly 10% from the Tories and 2% from Labour.
Seats (calculated by Electoral Calculus)
Labour 213
Conservatives 207
Alliance 205
NI Unionists 12
SNP/ PC/ SDLP 9
DUP 3
I went through each constituency on Wikipedia to get the breakdown of returned Liberal MPs as opposed to returned SDP MPs, and calculated 112 Liberals and 93 SDP.
POD would be no Falklands War or the war somehow goes badly to the British, with unemployment as high as it was that would probably be enough but you can add other government misteps. Note that the Labour vote share is close enough to OTL that they really just need the Alliance as being seen as a more viable potential government.
So what happens next?