I think it would be fair to say that the idea of a Progressive Alliance originated in Green circles. Caroline Lucas made the case following the miserable election result in 2015 and although she was later supported by Clive Lewis from Labour and Layla Moran from the Liberal Democrats, she spoke on behalf of our party and as its leader. The whole idea of a Progressive Alliance is typical of our cooperative way of doing politics; pluralism runs deep in our culture and values. It was naïve of us, perhaps, to not anticipate the way it would be turned against us.

Labour failed to rise to the occasion and instead used the proposal for their party’s self-interest. They combined the Progressive Alliance with their GTTO (Get The Tories Out) mantra to demand that everybody except the strongest non-Tory party with the most votes must stand aside in every constituency. They put both Greens and Liberal Democrats under huge pressure in marginals where they claimed we were splitting the vote. They simultaneously refused to stand aside any of their candidates. They also put pressure on candidates in safe Tory seats and safe Labour seats. They were simply using our willingness to cooperate to try to remove us from the contest.

To say that Green activists are now wary of the idea of electoral alliances would be an understatement. Many have been burned and are deeply disillusioned by the experience. Not only are we the party whose voters are most outrageously under-represented but we are also the party that comes under most pressure to ‘stand aside’. The table shows the inequities of the electoral system that we know so well: in the UK it is not how you vote but where you vote that really counts. In a context where Green support is growing and Green voters are so under-represented, the high-handed suggestion that we should not offer our inspiring platform of policies like wealth tax, strong laws to protect nature and wildlife, a fair asylum system, public ownership, and self-ID – policies that Labour are currently running a mile from – is as undemocratic as it is predictable.

But we are not fools. We can do the electoral maths as well as anybody else and we recognise as clearly the desperate state the country is in. It’s partly for this reason that we would like any future electoral agreement to ensure that we have a genuinely pluralist government, using the best proposals from all the progressive parties to solve the towering inferno of crises the country is facing. Any Progressive Alliance that could be supported by the Green Party would need to ensure that the MPs elected to the new Parliament would reflect as closely as possible the electoral preferences of the voters. This would have to mean Greens being given priority in some winnable seats and other parties involved in the alliance agreeing to dial back their campaigns there. In short, we would like to see a Progressive Alliance that enabled the UK to behave more like a democracy.

This links to the second point, which is that any Progressive Alliance must have at its heart an understanding that this is only a first step towards significant constitutional reform, beginning with a fair voting system. No candidate should be asked to stand aside or support any other candidate who was not clearly committed to a proportional electoral system. We might extend this to party manifestos.

It’s clear that Labour and Liberal Democrats have some kind of informal arrangement about targeting their resources. There is no reason that they could not bring the Greens into that. It is already obvious which seats we are targeting, and that they are a fairly small number. If we had some guarantees of the other parties avoiding those constituencies we might – even at this late stage – offer some quid pro quos in terms of marginal seats elsewhere.

How these progressive alliances are publicised and framed also matters. Tactical voting is anathema to a true democrat – encouraging people to gamble on outcomes rather than vote on principle, it feeds a raft of charlatans and chancers. Any platform that hopes to be taken seriously would have to frame the arrangement in terms of a temporary step towards enhancing democracy, not just a means to Get the Tories Out. As a minimum, tactical voting sites would have to find some way of addressing the electoral imbalance against the Greens. And they should avoid making recommendations in seats that are safe for any party, thus avoiding tactical vote being used as a mean of artificially suppressing the support for other opposition parties.

As Greens we are seeking to live in a flourishing, pluralist and inclusive democracy. As Labour looks more and more like Tory-lite and as its leadership operates in an increasingly authoritarian way, we have no faith that they will offer this. But their membership has clearly demonstrated that they share the Green vision of how our democracy could work. The challenge for those who support a Progressive Alliance is to mobilise that sleeping giant and use it to build a progressive democracy in spite of the stranglehold of the two main parties.