I thought AV+ was the Scotish parliament etc system but with AV for constituencies instead of FPTP
not that AV's any good anyway, given that you only get two preferences
personally, I back STV, which I'm assuming the LibDems and Greens back, given that they're affiliated to the Electoral Reform Society. It would probably give the BNP 3 to 5 seats (possibly more on a very bad day) but we need to consider whether it's worth that cost, which I think it is, as long as they stay at around their present vote and the Tories and UKIP stick to any cordon sanitaire
Scottish parliament uses additional members system- a top up list where you need about 7% of the list vote to get elected in a region- with regions being roughly area of 800,000 people. Similar system in London as well for the GLA top up lists
http://www.scottish.parliament.uk/vli/education/resources/learningResources/propRep.htm
The disadvantage in England would be a lot more than 3 BNP MPs based on their June performance. Say in the NW, and assuming regional constituencys would be say 5-6 local authority areas, you would very likely get them elected in Cumbria, City of Manchester, Northern Greater Manchester, and East Lancashire. As they only polled less than 5% in 3 of the 39 local authority areas in the NW in June - I would guestimate maybe 4 MPs in the NW alone and 15 nationwide
