Now electoral reform for the Commons has been defeated, First Past the Post (FPTP) is with us for the foreseeable future. I was never convinced that Alternative Vote (AV) would be a game changer for smaller parties, but the current system is particularly bad for them.
There’s no doubt that FPTP exaggerates results. Below a certain share of the national vote, parties get fewer seats than they would under a proportional system. Above that level, they get more.
Yet the Greens do have one MP, and they are in fact less hard done by under FPTP than the other UK-wide parties of similar size: UKIP and the BNP.
In the 2010 election, the Greens nationally won 286k votes (1.0%); UKIP won 920k (3.1%); and the BNP 564k (1.9%). Yet of the three, only the Greens won a seat.
So, why was this the case, and what are the Greens’ prospects under FPTP?
To win a seat in a multi-way marginal, a party typically needs at least 30%. Caroline Lucas won Brighton Pavilion with 31%; the next target for the Greens, Norwich South, was won by the Lib Dems with 29%.
Yet, with a lower national share than UKIP and the BNP, explanation is needed for why the Greens were able to mobilise 31% in a particular constituency, while the others were not able to do so.
At least part of the answer is suggested by the huge poll conducted by Lord Ashcroft, in particular the question on how likely respondents are to vote for various parties, on a 10-point scale.
The proportions who say they are extremely likely (let’s say 9 or 10) to vote for each of the three small parties is roughly what we’d expect: small, and similar to one another.
But the differences are very interesting when we look lower down the scale: