Only weeks ago, Leave campaigners were calling for the British people to “take back control” of our democracy. Now, in the shadow of an outpouring of anger at deals done behind closed doors, the British have a Prime Minister who was chosen only by Conservative MPs.

The political developments of recent weeks have rightly amplified calls for a general election to be held in the autumn. It is crucial that those negotiating Brexit on our behalf have a mandate from the general public, and Theresa May has none.

However, the prospect of an election in the coming months makes even more urgent the need for a progressive alliance. It is clear that Labour, having been wiped out in Scotland and with constituency boundary changes on the way, simply cannot win a general election alone. All those who want to protect Britain from the damage that would be caused by a Brexit deal negotiated by a cabal of senior Tories, must work together to make an alternative possible.

A progressive alliance means parties who share common values and aims working together to maximise their chances of getting elected, and then forming a government that can put an agreed set of policies into practice. The Green Party is calling for such an alliance with the Labour Party, the SNP, Plaid Cymru, the Liberal Democrats and other progressive parties, with the aim of preventing the formation of a Conservative-Ukip-DUP government that would seek to enact an ultra-right Brexit.

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A progressive alliance must not be a deal done behind closed doors: only 24 per cent of the electorate voted for the Conservatives, and no-one voted for Prime Minister Theresa May. It’s crucial that as many people as possible – Leave and Remain voters alike – are represented by the government that is responsible for leading us through the Brexit negotiations.

There are many different ways a progressive alliance could work. For example, open primaries could be held in marginal seats to allow voters to choose a progressive candidate. Or parties could agree on which seats it would be most beneficial for them each to target. But whatever the arrangement, it must be worked out by local parties in conversation with one another, and not dictated by party leaders.

Any such deal would, however, include some shared policy commitments. For the Green Party, our priority is electoral reform.

I believe that the Brexit vote was in part a result of the frustration and disenfranchisement caused by an electoral system which leaves the majority of voters unrepresented. Whatever your politics, it’s clear that 4 million Ukip voters winning only one MP, while just under 1.5 million votes for the SNP gave them control of almost every seat in Scotland, shows that our democracy isn’t working for most voters.

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One of the first steps to reconciling the huge divisions in our society and restoring the trust in politics – which has so obviously been lost – must be to build a system which genuinely puts power back in voters’ hands.

A progressive alliance must also commit to reversing the shift of wealth and income from the very richest to the majority; ending the privatisation of the NHS; major investment in truly affordable housing, renewable energy, insulation and infrastructure, creating well paid and useful jobs in every constituency.

If there has ever been a time to leave tribal politics behind, it is now. In more than 50 years in politics, in the US and UK, I have never seen such an extraordinary period.

We face huge risks. But we also have a huge opportunity to break out of this dysfunctional system and create a more equal, more inclusive democracy.