The UK will vote on May 5th on whether to switch to the Alternative Vote system (AV) rather than the current First Past The Post (FPTP). I'm a supporter of AV, but FPTP has huge support from both the major parties and from Rupert Murdoch, which means that it both doesn't have a chance and must be the right way on principal.

Fact is anything legal that Murdoch's against I'm for on principal.

There has been a lot of misinformation about this: lots of bad examples in every media outlet trying to make AV seem much more complicated than it is, and no clear explanation as to why anyone would want the switch in the first place.

So here's my go: imagine a typical UK voting scenario at the next election. There are 6 candidates:

• Conservative - centre right, currently in power, conflicted on EU.
• Labour - slightly less right than the Conservatives but more authoritarian
• Liberal Democrat - centre left, but lie a lot.
• Green Party - left wing and pro environment, but tiny.
• UKIP - right wing and isolationist.
• BNP - left wing and openly racist.

FPTP

Under the current FPTP system you cast your vote for one of the above, but you have a problem if you don't support either of the top two.

For instance I'm left wing, but I don't think much of the Labour party. The Green Party is closest to my political views. However, a vote for the Greens is a wasted one - only Conservative and Labour have any real chance of winning. I end up voting Labour, as despite the fact that they're my third choice I would still rather see them win than the Conservatives.

This tactical voting isn't only a problem for me - suppose that someone is right wing economically but prefers UKIP's stance on the EU to the Conservative's? They'd have to vote Conservative tactically too.

In both cases the relevant mainstream party claims the voter's support - there's no visibility that they were nobody's first choice.

Despite all that tactical voting most voters will have gone for someone other than the candidate that wins - with 6 candidates that could be less than 20% of the votes!

AV

So under AV that changes - instead of one X in a box we put all 6 candidates in order. I put my first choice down as the Green Party, then Lib Dem, then Labour. My right wing counterpart chooses UKIP, then Conservative.

1. Greens have the fewest votes - my vote falls back to Lib Dems, my second choice.
2. BNP have the next fewest.
3. UKIP are next - my counterpart's vote falls back to Conservative.
4. Lib Dems are next, so my vote falls back again, this time to Labour

So after all that we still have either Labour or Conservative, but with two very important differences:

• The winner has 50% of all the votes cast.
• Everyone gets access to the voting stats, so everyone knows how much support each party actually has.

That second point is important for all the smaller parties - for instance the BNP would see that they have a very small number of first choices and that everyone else lists them last (incidentally the BNP are dead against AV, despite what the anti-AV lobbyists say). Lots of small single issue parties would be able to show that there is support for their issue, even if not enough to elect them on that alone. Lots of alternate parties like the Greens and UKIP could accurately gauge their support. Lots of independent candidates could stand despite not having national backing.

Most seats in the UK don't have that much choice - my local MP at the last election was a choice of Lib Dem, Labour or Conservative, and the Conservative's took it by a very slim margin. Arguable the left-wing vote was split across two parties while the right-wing voter only had one choice. Likewise there were plenty of seats with a choice of Labour, Conservative or UKIP where Labour got in, this time because the right-wing vote was split.

In fact in the last election there were several marginal seats where smaller parties didn't even field a candidate for fear of splitting the left or right voting blocks.

More fine grain choice of political parties shouldn't reduce your chances of success!

So why are the big parties so against this? Well, long term it breaks down their monopoly - it will be easier to gain support for smaller parties. It will make election outcomes considerably more unpredictable - MPs will have to work harder for your vote because it will mean more. Surely MPs having to work harder can only be a good thing?