This week will see the UK Parliament debate a bill to give the voters a referendum on electoral reform. It's 35 years since Britain last had a national referendum, and the one proposed for next May clearly hasn't had the most auspicious beginnings. In fact anyone expecting to have a real say in how the country is run is likely to be disappointed. The politicians are planning to offer us two flavours of vanilla: genuine reform is not on the menu.
At the moment, the UK uses four different voting systems in national elections: first past the post for Westminster; AMS (Additional Member System) for the Scottish Parliament and Welsh Assembly; regional party lists for the European Elections; and STV (Single Transferable Vote) in Northern Ireland.
But the proposed referendum question is merely a choice between first past the post and Additional Vote (AV): in other words, a system unfamiliar to UK voters and which, until the last few months, has had few supporters. The last major review of voting systems, the Jenkins Commission, proposed another system: AV Plus. The Electoral Reform Society campaigns for STV, which is the system to which the Lib Dems were committed in this year's general election.
So we have a situation in which the two coalition parties – neither of whom included AV in their manifestos – are supporting a referendum for one system, while Labour, which made a belated conversion to AV before the election, is against it.
How has this come about? Sadly, the only explanation is old-style politics. The Conservatives don't want to change the current system, and are allowing the referendum to shore up the coalition in the hope that the country will vote No. To them, AV is more acceptable than a genuinely proportional system because it minimises the risk of Ukip winning any seats at their expense. The Liberal Democrats have dropped STV, comforted by the fact that AV will benefit them more than anyone else. And Labour can drop its commitment to reform while blaming the government.
My own party, the Greens, supports the Additional Member System – a system which is more proportional but which maintains a constituency link. We'll be deciding our position on AV at our forthcoming conference. But I believe that the most important priority is to give the public a real choice. Otherwise, people will remain cynical and disengaged. That is why I will be tabling an amendment in Parliament to rewrite the question to allow people to choose between AV, AMS, STV and the party list system, or to stick with first past the post.
I hope MPs of all parties who support reform will back this amendment. And in particular, as the Labour leadership battle narrows in favour of the Miliband brothers, I challenge them to support my amendment, to demonstrate their commitment to both pluralism and democracy. AV may have some advantages over first past the post, but it is unlikely to shake up politics and in some circumstances can be even less proportional than the current system. Analysis by the House of Commons library suggests that if the 1997 election, for example, had been fought under AV, it would have given Labour an even more massive majority.
May 2011 is not only the planned date of the referendum: it will also be two years since the MPs expenses scandal first broke. Parliament has come to be seen with contempt by many people because it acted in its own interests, not those of the people it is supposed to serve. A stitched-up referendum that denies people a real choice stinks of the old politics. All MPs, including those who support first past the post, should see that unless the public has a real choice, a chance to restore trust in politics will have been lost. But if politicians put aside their own instincts and interests and trust the people, Parliament could win back some of that lost trust.
The writer is leader of the Green Party and MP for Brighton Pavilion