Creating an economy for people not profit, ensuring equality for women, ending racism, stopping the destruction of our environment are all among the vital tasks facing the progressive movement. We must find ways to ensure we can support all these ends. And that must mean a politics that brings the movements arguing for change together with those who can make it happen both in and outside Parliament.

That requires political parties that can articulate the demands of movements through the political process.

When we engage in political action there are a number of important ways in which we can make changes happen. For me, as for many Greens, political action should not be limited to the sphere of parliamentary politics and elections. Our politics must draw from the progressive movements that have always driven social change. For much of the period after the industrial revolution that has been the trade union movement. But the changes the trade union movement have fought for and won are not the only significant victories. One of the key issues James raises is that of the need for a working class party with links to the trade unions.

But that’s not enough. We have a working class party with links to trade unions, so do many other western countries. Yet the solutions to the problems I set out above, while they may be closer, are by no means ready to be implemented. We need a way for progressive movements to ensure that changes happen. The social democratic parties have been weak on issues like women’s equality, the environment, and even workers’ rights for too long. There needs to be parliamentary and electoral pressure on these parties.

In the UK, the Labour party’s drift away from progressive politics has been helped enormously by the absence from parliament of a serious and organised progressive alternative. In countries where there are parliamentary forces that progressive movements can mobilise to ideological ends, we have another lever that can push progressive change. SYRIZA are the best example of such a formation, but the Front de Gauche in France have also been effective at pulling the French Socialist Party to the left.

While it is unclear what the mechanism for internal change in the Labour Party is, the only strategic option for those who want a progressive politics is to exert external pressure on the Labour Party. I’m still unclear, other than the call for more party democracy, or for more left-wing MPs as ‘ends in themselves’ how the 30 year long drift of the Labour party to the right is to be reversed. And even with a halt to the move to the right, even the Labour Party at the height of its progressive power didn’t publicly support workers on strike.

At the next election Labour is promising no reversal of cuts to legal aid, student fees of £6000 and hasn’t made any clear commitment to the de-marketisation of the NHS. I’m not sure why anyone on the left could or should ever vote for those policies, however working class the party advocating them is.

Of course, there is little stopping the Labour Party from changing its policy on these things. None of them are necessary to the politics we need to create. But the fact that the Labour Party leadership makes a new and disappointing policy announcement almost every day suggests that the outcome of voting Labour will not be the creation of a politics that delivers for people, but a politics that continues the corporate-led hollowing out of Westminster politics.

We must not lose sight of the achievements of social movements. Without the contribution of the women’s movement, environmentalists, anti-racist activists the Labour Party and trade union movement could not have achieved what it has. We must continue to build both within and outside the labour movement. While the labour movement must be an arena of struggle for activists, we need to ensure that wider forces act on that movement. And the same is true of the Labour Party itself.

In Scotland the student movement has achieved the abolition of fees, using the Scottish Green Party and SNP to push Labour into an announcement that it won’t introduce fees in Scotland, despite wanting £6,000 a year fees in England. This shows how social movements can use progressive elements in parliament to achieve social change. Without Greens this wouldn’t have been possible.

Until there is any mechanism by which the Labour Party can be made to act in the interests of those who founded the party, and who are meant to be its beneficiaries, it is hard to see how it can be won back. While there may be constituencies where voting Labour represents the best tactical choice to beat the Tories this time round, it must be the task of those who want a broader progressive politics to put pressure on Labour from outside the party. That means organising in social movements – we need a future that is radical, feminist and green. And it means building an electoral alternative to Labour. In many cases it will mean voting for parties, like the Greens, parties who articulate the policies and politics that the Labour Party was set up to represent.

Had progressives in Greece directed all their attention at Labour’s sister-party, PASOK, there would have been no SYRIZA government to make the case against austerity. While that may be in the interests of those on the right of the Labour Party, it makes no sense for the left. There is the opportunity for the left to win back the Labour Party, but it’s hard to see how that can happen without electoral and parliamentary pressure from the left.

And the long term interests of the working class and the mass of the people are best served by strengthening parties and movements that best represent those interests. That will mean a party that has the sort of left-wing policies and politics the Labour Party has long since abandoned.

The efforts of activists in the Greens will be rewarded with a party that makes the case for free education, equality for women and other excluded groups, for the retention of a social security system, for a massive house-building programme and for serious action on climate change. Having a party in which decisions are made democratically makes radical change much easier. The more votes for such a party, the more likely Labour will be to abandon its centrism and start to serve the interests of working people.

Working to build a Green Party of the left will create a buttress for social progress. Significant numbers of Green votes will help the case for a progressive politics, and create the necessary pressure for a radical leftward shift in the Labour Party’s policy and politics.

  • Peter McColl is the Scottish Green Parties lead Westminster candidate for 2015.  This is the second post in Lab vs. Green – a series debating which political parties progressive activists should get behind in the 2015 UK election.