The Tories have made an offer to the Lib Dems of a referendum on the alternative vote (AV) system.
I am not a supporter of AV. The fact that Labour and Tories can both support it, is a good indicator that it is not much of an improvement. Under AV you get to note a second choice on your ballot paper. The bottom candidate is eliminated and their second preferences re-allocated, until somebody gets over 50% of votes cast.
This system does not address the problem of proportionality – that the percentage of seats in parliament should broadly reflect the percentage of national votes cast. It is expected it would slightly improve proportionality, but that is a side effect and not inevitable. Indeed it can exagerrate the seat share of a dominant party. It most definitely does not help smaller parties, but rather tends to promote a flight to mediocrity – it puts a premium on being unobjectionable rather than exciting or different.
Party list systems are proportional, but I find them the worst of all as the parties can promote individual candidates who are personally unpalatable to the electorate. Under party list systems seats are allocated to parties according to the national or regional percentage of votes cast, and then those party seats are filled by the returning officer ticking down a party candidates list. The voter is voting for a party, not an individual.
The Scots system is a combination of AV, regionally topped up to add a proportional element from a party list. This is a horrible system.
By far the best system is single transferable vote in multi-member constituencies (STV). Under this system. large constituencies contain perhaps six or seven MPs. The voter gets a list of all candidates from all parties, and independents, and the voter can rank the actual individual candidates in order of preference from 1 to x. In a seven member constituency, a candidates needs 14.3% of the vote to be elected. If anyone gets that, their excess vote is distributed according to their second preferences, otherwise the person who came last is eliminated and their preferences distributed, ad infintum until you have seven people elected.
This gives a strongly proportional result nationally, encourages small parties and independent candidates, and gives the voter a wide choice of individual candidates.
The most quoted disadvantages of STV are the loss of the link between an MP and their small constituency, and the encouragement to the BNP.
On the constituency link, I think this is romantic tosh. Only the expenses scandal caused any signficant proportion of the electorate to be able to name their own MP. MPs would still have a strong regional link.
On the BNP, there is no region where they came anywhere near to getting 16%. But I am afraid to say that should the BNP be able to get that kind of level of support, I think they would be entitled to their MP.
So there we have it. In my view, STV is by far the best system and the only one worth changing to. I don’t believe AV is significantly better than FPTP.