Last week, more than at any time I can remember, politically active friends from across the left – from the feminist, student, anti-austerity, environmental and democracy movements, seem to have turned out in droves to vote for The Green Party. This is an appeal to them – you – to join the party, and to get involved.

Perhaps it seems obvious to you why you might. Maybe you’ve long been looking for a party which wants a democratic transformation of the economy; which supports free education and will defend the NHS; wants to cap rents and bring back council housing; fight to keep oil in the ground and stand up to austerity, the banks, corporate power and the frightening growth in inequality; a party which won’t pander to the scapegoating of migrants or people on benefits, and will point the finger of blame firmly where it belongs: at the powerful; a party which brings together ideas from the feminist, anti-racist, environmental, disabled people’s and working class movements, radical democratic movements, the peace movement, the LGBTIQ movement, and so on.

Maybe you can already see why you’d want to be a member of a party which allows its membership to set its policies democratically; around the core principles of radical democracy, equality, social justice, peace and the environment?

That party exists. It came 4th in the European elections. You can read its most recent manifesto here. If it’s obvious to you why you’d want to join, stop reading and go and do it (or, if you’re in Scotland, here or in Northern Ireland, here).

Parties are about more than elections, but engaging in electoral politics is one key thing they do, and I think more of us need to start doing just that. It’s one tactic among many. It should never come at the exclusion of other political tools, but to avoid using elections is, I think, a big mistake – for a few reasons.

Firstly, elections drive much of the political agenda. Even most modern civil disobedience – think UK Uncut or much of climate camp – aims primarily to shift debate rather than actually disrupt permanently. If this is what you want to do, then why would you ignore such a huge inroad into the national conversation as elections? If you’re a genuine anarchist, I can understand. Otherwise, I don’t.

Secondly, getting prominent spokespeople into council chambers and parliaments is vital. Was it Lenin who said something like “even a pile of horse shit can make a good stage to stand on”? This isn’t just about getting MPs onto Question Time. The main role of a local councillor is being a (minimally) paid organiser. If you want to engage in political action in your community, being given a small salary and a minor platform is hugely helpful. Without infrastructure, movements dwindle rapidly. Councillors are a good way to get it.

Thirdly, elections force you to talk to people. You don’t win (if you’re on the left) unless you knock on doors and chat. It is, of course, entirely possible to do this without elections. But the people I know who actually get round to it frequently out-with the electoral process are few and far between.

Ultimately, by standing in elections, you take votes away from the powerful, which forces them to win those votes back off you, driving politics in a progressive direction – and, ultimately, you might gain some power – which, ideally, you’ll then work to hand to the community you represent as fast as possible.

You can stand in elections without joining a political party, but if you are interested in a broad political project, in grouping together with people with similar ideology to you and getting them elected too, and in developing a programme for how you might change things, then that’s what a political party is and does.

And parties are about more than elections. Politics requires infrastructure. It needs people who will organise rotas for who is going to go and reach out to whom, places that as yet uninvolved people can come to meet and organise with those of similar ideology, spaces for people to get a political education, think about what they believe and together work out what they want to do in the world. It needs us to come together across generations and beyond our groups of friends – with those whose routes were different from ours, and so are coming from slightly different places. Parties do all of these things.

In short, our social movements need an electoral expression. If you wish to change the world (and surely we must), I think you should probably join a party – not as the exclusive output for your politics, but as one of them.

Why the Green Party? I’m not going to rehearse the arguments against Labour here. Suffice to say that even in those areas in which they ought to be strongest, they are pathetic: Greens have supported more strikes in the last fortnight than Labour has in its whole history. I hope the next government is Labour rather than Tory, and I think we should all seek to encourage it to do better, but I think more influence is placed on them from outside than inside – if they can get your support without changing their position, that’s what they’ll do. Perhaps most importantly, as anger with the establishment soars, I don’t understand why radicals would side with the establishment.

The case against Lib Dems is obvious. Respect have vanished, and No2EU’s performance showed little hope of the march of a new socialist party of that ilk. In the elections last week, the Green Party showed it was more able to unite the left than Left Unity ever has and National Health Action is a genuine single issue party with no ideological platform, much as it’s a vital issue, much as I hope they do well where they stand.

More importantly, Greens reflect better than any other party what I would see as the shared values of much of what you might call the activist left of my generation. The party is radical in its economics – aiming to socialise financial institutions, nationalise public services and monopolies and defend trade union and workers’ rights – but has learnt the lessons the left needs to learn. It is founded on the principle of decentralist democracy and power to the people, rather than believing that the alienation of markets can be defeated only with the bureaucracy of the state. It supports a citizens’ income, a workers’ right to turn their company into a co-op. It is feminist, anti-racist, and has always stood for LGBTIQ rights.

It does have problems. One is that it is seen solely as being ‘about the environment’. But it is beginning to challenge that perception, and the more people who join it from across radical politics, the more it will articulate a broad vision for society. Of course we must save the planet, but we’ll only do that by changing the system. Another is that it needs better to involve and be led by people of colour. With this, in particular, we need help from new members.

But as I have argued, the election results last week showed something remarkable. Greens came (admittedly distant) second across Manchester and are now the opposition in Liverpool, Solihul, Lewisham, Islington and Norwich. We came first across not just Brighton Pavilion constituency, but also Bristol West and Norwich South and very nearly Glasgow Kelvin. We won a seat in a Belfast City council ward so big that on its own it gives us a good chance of winning a second seat in the Northern Irish Assembly, and one of Northern Ireland’s leading feminists very narrowly missed out on picking up another seat, apparently in the face of opponents (from the Labour affiliated SDLP) telling voters that she wanted to kill babies because of her prominent and vocal campaigning for the right to an abortion in one of the few parts of the EU in which it is still denied.

The party had a vast number of candidates standing in the local elections – we ran in all but one seat in the Wirral, in most seats in Carlisle, St Helens, Southampton, almost every ward I could find results for in London in hours of googling. In fact, though I’m sure they exist, I am yet to find a town or city in England which had local council elections last week and in which Greens didn’t stand in most or many wards. Apart from the more left wing trades unions (you should certainly join one of them too) how many genuinely radical, member-run organisations have anything like that reach on the ground?

Finally, it’s important to understand how much difference you can make by joining and becoming active in the party. Greens got an MEP in the South West of England this week. A significant part of that success comes down to the rise of the Bristol Greens. Whilst they have mobilised significant support, I could list a handful of people who, together, have made that happen. Across the country, other Greens missed out by a few votes. A group of four or five people in a couple more towns, cities or areas of those regions could have persuaded enough people to make the difference. Last week, five friends and I got two city councillors elected in Oxford – two people who will now be political organisers for four years, bringing infrastructure and activity to the communities they represent. As British politics contorts itself in the wake of the UKIP Euro-victory, we’re going to need to organise ourselves into a large, national, sustained and vocal response. There is no need to start from scratch in building this.

If you do join the Green Party, I guarantee you that you will find people you disagree with. I assure you that you that you will find yourself frustrated at times. Because politics is a collective endeavour, and people can be bloody annoying. But ultimately, if we’re going to change the world, then we’re going to have to do it together, including with some people who have slightly different priorities from us.

Likewise, I am sure every member disagrees with some of the party’s positions. But there’s a democratic process for debating and changing policies, and the activities are driven by voluntary members. It’s not because the party is perfect that you should get involved, but to help build it up, to improve it. There has to be a compromise between on the one hand the vast and centralised tent that is the Labour party and splintering like Trotskyites each time we disagree.

Over the last five years, the membership of the Green Party of England and Wales has more than doubled. Largely, that new intake is young, radical, and impressively good at organising. It’s people from the anti-austerity movement, the student movement, the feminist movement. I’ve been a paid up Green half my life. I’ve never known such a thrilling time to be in the party. Conversely, with UKIP on the march, I’ve never known a scarier time in politics. It’s time to join us.

If you’re in England and Wales, you can do it here. If you’re Scottish, here. If you’re Northern Irish, here. Go on. It’s time.