19/05/2015 16:38 BST | Updated 19/05/2016 06:59 BST

From Town Halls to Westminster, We Need Proportional Representation

On Monday I joined Green Party deputy leader Amelia Womack and representatives from four other parties in presenting to David Cameron two petitions with more than 350,000 signatures calling for reform of the electoral system that caused the most disproportional result from a Westminster election ever.

For the Green Party the maths is simple. Our more than 1.1million votes would, under a proportional system, have delivered 24 seats. Instead we got just one - the return of the brilliant MP for Brighton Pavilion, Caroline Lucas.

London would have three or four Green MPs - the number of Green Assembly members it could see next year, under the Additional Member System used for these proportional elections, which have never seen fewer than two Greens on the Assembly since its creation.

In a multiparty democracy first-past-the-post, a failed system for decades, is clearly comprehensively out of date.

Overall, in this election the Tories won just over one third of the vote, 37%, but more than half the seats. And that's without considering the fact that more than 30% of eligible people chose not to vote.

Our current government has the backing of less than a quarter of the electorate.

The problems with our political system go deeper than the electoral system, but certainly a significant number of those non-voters feel that, living in "safe seats", it's not worth their bother voting, and it is easy to understand their position.

Opponents of reform often claim that other systems are "too complex" for voters to understand, but Scottish, Welsh and London voters are managing perfectly well - and what could be simpler or clearer than a system where if you get 10% of the votes, you get 10% of the seats in parliament?

Vote for what you believe in, and get it: that's the system we need.

The focus yesterday, rightly, was on Westminster, where there's been no significant reform since women got the vote in 1918. It would be nice to make a national vow not to get to the centenary of that important event without real change.

But there's another issue, even more mathematically striking - local government elections. Their results from first-past-the-post can be even more divorced from the voters' wishes.

Take Bournemouth. Now I can only say congratulations to the local Green Party, which won its first-ever council seat (by a nerve-wrackingly narrow margin) after a recount.

But that one seat came from more than 25,000 votes, while elected Conservative councillors, an overwhelming majority, collected an average of fewer than 2,000 votes each.

That was in its way, however, a fairer result than last year in Hackney, where the Green Party won 20.5% of the vote, but no seats, while the Labour Party took 88% of seats from 58% of the vote.

And on Crewkerne (Somerset) town council, the Green Party's candidates won 31% of the votes, but no seats on the council. The Lib Dems hold 11 of the 12 seats.

By contrast, in Scotland, elections are held through the proportional Single Transferable Vote method - and deliver fair results.

Electoral reform can seem to be a rather technical subject, hardly a popular cause that is likely to get hundreds of thousands out on the streets, but it is clear that our current system is not working at Westminster nor local council level.

It's part of the reason why our politics is failing to deliver for the common good, with the largest parties focusing their attention and policies on swing voters in swing seats.

This is a campaign that needs to be high-profile, vocal, and led by civil society actors like the Electoral Reform Society and Unlock Democracy, with the backing of everyone who understands the need for real change in our failed political system.

It's not easy to see the exact route by which reform could be achieved - given we now have a majority Tory government in which a significant number of members enjoy the cushion of safe seats.

But it's a tiny majority of 12, likely to soon fall apart. The whole of Westminster is currently febrile and unstable - change must come, so it will come, and the more we keep up the pressure, the more likely it is to happen, and the more likely that it will produce a truly democratic outcome.

The failed AV referendum came not from popular pressure but a Westminster stitch-up; keeping up the pressure means we can get a far better choice next time.