From the comments below on "BNP Fools":
I don't think the university graduates of the SWP understood the system either. Their Left List put out a leaflet saying: "The proportional representation system means the only way to stop a minor party like the BNP getting elected is to vote for a progressive, left alternative. Under the PR system just piling up voted for New Labour will not block the BNP. But voting for the Left List can stop the fascists getting a seat on the London Assembly". I think I'm right in saying that this is just not true. The D'Hondt system favours the bigger parties, so piling up votes for New Labour, the Tories, the Liberals or the Greens would precisely have been the way to have blocked the BNP. In this respect a vote for the SWP/Left List or any other very minor party would have been a wasted vote. Am I right or do you need a Ph D in statistics to understand all this?London Socialist is right.
In a sense what they are suggesting has some basis. In a PR system, every vote cast for a candidate other than the BNP does increase the chance of that party getting the seat instead of the BNP.
Further, with the 5% threshold, every vote cast changes absolutely the number of votes they would require in order to enter the assembly.
But, the d'Hondt system is superproportional for larger parties, and simply voting to big up the Labour vote would be more likely to help them snatch the seat to prevent the BNP from filling it.
The only way what the SWP were suggesting could work would be if there were large scale transfers from Labour to the Left List - this would be to take advantage of the additional member system, but if this had happened thoroughly, the SWP/Left List would have gained 8 seats with 650,000 votes, and the BNP would still have got in. Likewise, if the left did manage to pull of such a stunt, it's likely that the BNP would have been able to pull votes off the Tories.
As it is, the votes for the also rans (Christian Peoples Party, English Democrats, UKIP, Respect, Left List, One London) come to 228,214 - that represents about two seats, and probably represents, more or less, the super proportionality of the larger parties. The majority of these are right wing votes, and so would otherwise have fallen to the Tories. But, then, the aim is to keep the BNP out, so better Tories than fascists?
Mind, an extra 95,000 votes for Labour would have taken a seat off the Tories, which would in most terms mean a reduction in the potential voting weight of the BNP, since it would make it harder for them to act as the pivot on which a Tory majority could hang.
If you're going to play these games, at least play them right.