I would say that we are becoming increasingly pluralistic as an electorate. We have got used to voting for smaller parties and those often described as "others". I think the vote share of the two main parties will continue to decline and it will get harder and harder for them to justify the present system.
Mark’s post is titled ‘How low can we go?’, and I couldn’t resist thinking about an answer. What follows, as Peter Snow used to say, is just a bit of fun.
For reference, the 2005 election result:
C 33% (198 seats), L 36% (356), LD 23% (62), Others 8% (30)
Now, the latest Populus poll seems a fair place to start; feeding that into the seat calculator at Electoral Calculus, we get:
C 38% (341), L 26% (222), LD 20% (56), Oth 16% (31)
So despite a doubling of the minor parties’ vote, their seat tally is basically unchanged.
What I did next was gradually shift support away from the two main parties and towards the Lib Dems and others. I’ve taken a series of steps, each subtracting 1.5% from the Conservative vote and 1% from Labour and adding 1% to the Lib Dems and 1.5% to the others.
The result is s series of pie charts. The headings give the vote shares and the sizes of the slices show the number of MPs returned; the Conservatives are blue, Labour red, Lib Dems yellow and others green.
So, as the Labour/Tory vote erodes, the Lib Dems scoop up more and more seats, but the other parties hardly make headway, even at a quarter of the vote. And even when the Labour/Tory vote dips to 49%, they still hold just over three-quarters of the seats in parliament.
But then we reach what looks like a tipping point:
The Lib Dems continues their forward march (although even on becoming the most popular party, they still lag third in terms of seats), but now the minor parties really start to make advances as well.
From here on, the results splinter in all directions, and we can clearly say that even the three-party system is no more:
But of course this wouldn’t really happen, even if such mammoth shifts in votes did take place. There’d be massive local variation, and different minor parties would do well in different areas and against different main parties. But it’s an intriguing bit of Friday fun.
And now all this talk of pie has made me hungry...