Caroline Lucas​ became the Green Party’s first MP when she won Brighton Pavilion in 2010. Two years later she resigned as leader of the party in England and Wales and was replaced by Natalie Bennett. In 2011, the Greens took minority control of Brighton and Hove City Council, and in 2013 Jenny Jones, who has represented the Greens in the London Assembly since 2000, became a peer in the House of Lords. At the beginning of 2014, the party had 15,000 members; now the figure is closer to 60,000 (Ukip and the Lib Dems have about 45,000 each); most of the ‘Green surge’ took place in January, when there was a row about the leaders’ debates and whether Bennett should be included: in one week, the party gained 13,274 members. But there have been some embarrassing gaffes, the worst of them Bennett’s ‘brain fade’ when she was asked on LBC Radio to explain how the Greens planned to fund their housing policy. The dream for the party is to take three or four seats in the election, but a complete wipe-out isn’t impossible.

Here’s the difficulty for the Greens. Most people who are inclined to vote for them would also prefer a Labour government to a Conservative one. In a first past the post ballot, a vote for the Greens is therefore more likely to remove support from Labour than the Tories, and so makes a Tory victory more likely. Lucas’s book Honourable Friends?, part memoir and part manifesto, puts a lot of emphasis on the need for voting reform, but for the purposes of this election the Greens have had to resort to the standard arguments of small parties in first past the post systems. First, they make light of the differences between the main parties: ‘We have got a Labour Party that is barely distinguishable from the Tory-Lib Dem coalition,’ Bennett said in 2012; Labour and the Conservatives are just ‘two versions of market fundamentalism’ is the way George Monbiot put it. Second, the Greens argue that if large numbers of people vote for them, but the party is rewarded with little or no representation in Parliament, the government will come under increasing pressure to accept electoral reforms that would open the system up to a wider array of parties. Lucas believes that if Labour loses at this election because of a strong Green showing, it will be forced to accept electoral reform. But the Lib Dems have been saying things like this for decades. The fact is that few people are motivated by long-term strategic considerations when they cast their vote. They know that whatever they do, there will be a Tory or Labour-led government – and that saps the will to vote Green.

The origins of the Green Party in the UK go back to 1972, when Tony Whittaker, a former Conservative councillor, read an interview in Playboy with Paul Ehrlich. Ehrlich had made a career of warning against the consequences of population growth. (‘The battle to feed all of humanity is over,’ he wrote in 1968 in The Population Bomb. ‘In the 1970s and 1980s hundreds of millions of people will starve to death in spite of any crash programmes embarked upon now.’) Whittaker established a discussion group called the Club of Thirteen composed mostly of former Tories worried about population growth, the disruption of ecological processes and ‘the permissiveness of Soho’. The group established PEOPLE party, which in 1975 became the Ecology Party and then, in 1985, the UK Green Party (now replaced by the three closely associated but independent parties of England and Wales, Scotland, and Northern Ireland).

It was only in the run-up to the 1997 election that the party made explicit moves to occupy a position on the left. ‘The Green Party fits automatically into the space left by the new-look Labour Party,’ Peg Alexander, then the party speaker, said in 1995: ‘a space which needs our commitment to economic and social equality and justice.’ In the last 15 years, this attitude has been internalised by the party. In her first conference speech as leader, Bennett argued that the Greens ‘need to strengthen and support our trade unions … as Greens we need to ask the unions “What can we do for you?”’ The current election manifesto begins with a promise to end austerity, and to pay for it by introducing a wealth tax and a tax on the banks. There are further undertakings: to end the privatisation of the NHS; to scrap university tuition fees and bring academies and free schools under local authority control; to introduce rent caps; and to renationalise the railways.

One proposal that made it into the manifesto only as an aspiration was the citizen’s income, a basic income paid to all citizens regardless of financial circumstances, which would replace personal tax allowances and benefits other than disability and housing. The policy had been part of the party’s platform since its earliest days, but research has indicated that unless it were means-tested, many poor households could end up losing more than 10 per cent of their current income. The reason the Greens hadn’t foreseen the difficulty is a consequence of their ideological reorientation. The policy wasn’t originally conceived as a straightforward redistributive measure: it was designed instead to cushion people from the economic decline the Greens both anticipated and hoped for (more about that shortly). If people’s basic needs were taken care of, so the thinking went, they would be less anxious, less inclined to behave aggressively towards others or to exploit the environment: ‘individuals, through their ability to satisfy their basic needs more fully, are … able better to contribute to future sustainability.’

Another idea that has survived since the Greens were formed is that governments shouldn’t be aiming to achieve economic growth. From the Greens’ point of view, Labour and the Conservatives share a ‘super-ideology’ of industrialism which holds that people are best served by economic growth; the two parties merely disagree about the distribution of wealth and power that results. For the Greens, such concerns will soon be overtaken by events – by pollution, resource depletion and climate change, which will make traditional politics seem like a rearranging of the deckchairs on the Titanic. The economy, Lucas writes, ‘is a subsystem of the biosphere, and … since the biosphere isn’t getting any larger, the subsystem has to remain within limits’. Instead of growth, we need to move to a steady-state economy. The mainstream parties believe this is a fantasy. ‘It’s our opponents who are the fantasists,’ the Green manifesto declares, because they believe that ‘continual growth is possible on a finite planet.’

Critics of the Greens argue that they don’t take proper account of technological progress. Optimists believe that human ingenuity will sustain us indefinitely, even if current patterns of consumption continue. New technologies, like wind power or carbon capture and storage, make industries cleaner; if we run out of natural resources, we will locate new ones or develop substitutes. From the Green perspective, technology will only ever be able to defer the crisis for a limited number of years. Advances that make environmental savings in one area tend to increase the pressure in others: if you increase fuel economy in cars, people might drive further to work; nuclear power might reduce greenhouse gas emissions in the short term, but the extra energy supply will result in faster consumption of resources in other parts of the economy. It’s unclear whether this analysis applies to renewable energy as well. Even the Greens’ attitude to recycling is equivocal: it remains a ‘last resort’ in the 2015 manifesto. ‘The fiction of combining present levels of consumption with “limitless recycling” is more characteristic of the technocratic vision than of an ecological one,’ Jonathon Porritt, a long-time chair of the Ecology Party, wrote in 1984: ‘Recycling itself uses resources, expends energy, creates thermal pollution; on the bottom line, it’s just an industrial activity like all the others. Recycling is both useful and necessary – but it is an illusion to imagine that it provides any basic answers.’

Basic answers for the Greens have to do with reducing consumption and arriving at what Lucas calls ‘a post-growth world … based not only on efficiency, but on sufficiency: on having enough’. An end to economic growth would focus our minds on things that matter instead of on consumption and capital accumulation. We can have ‘qualitative development, but not aggregate quantitative growth’. Lucas argues that the way to achieve this is to ‘reverse engineer’ the economy: to work out what we really need in terms of sustainability, well-being, working hours and so on, and then work backwards to design an economy geared to produce those results. The Greens are committed to participatory democracy, but if we are to manage this reverse engineering without the more traditional consequences of a decline in economic growth (job losses and poverty), then we will have to leave a lot to the experts – and that is a technocratic solution, not a democratic one.

Not only is this way of thinking internally inconsistent, it is an awkward fit with the traditional left: Lucas is critical of the unions in so far as their promotion of industry conflicts with the Greens’ drive to reduce pollution and economic growth; the Greens’ appeal to the working class has been an almost complete failure. Green supporters remain disproportionately young, educated, middle-class and female, and it isn’t clear that there is any position on the traditional political spectrum that the party can comfortably occupy.

Lucas begins her book by quoting Petra Kelly, one of the founders of the German Greens: ‘We can no longer rely on the established parties, nor can we go on working solely through extra-parliamentary channels. There is a need for a new force, both in Parliament and outside it.’ This new force would be an ‘anti-party’ party: one, in Lucas’s words, ‘that would seek power but never sacrifice morality; that would enter Parliament but never become part of it; that would always remain, at heart, a party of the people’. Many, even within the party, are sceptical that an ‘anti-party’ party can keep its identity when it gains power. Will they be able to enter a system defined by centralised power without succumbing to the kinds of compromise and hypocrisy they reject in the other parties? Lucas has been a successful MP, but if the Greens do gain seats in this election, she may discover that some things are more easily achieved on one’s own: one of them is maintaining an ‘anti-party’ image.

In 2011, the Greens took minority control of Brighton and Hove City Council. The results have left the party open to questions about its fitness to wield power. It has attracted a lot of unwanted attention over the bin strikes which began in 2013 when the council’s attempt to enforce equal pay legislation resulted in a substantial net loss of income for hundreds of refuse workers. In the summer of 2013, rubbish piled up on the streets, and the dispute has rumbled on ever since. There have also been internal divisions. Labour likes to talk about ‘Caroline’s council’, but Lucas supported the unions during the strikes. And there has been some of the plotting and backchannelling that the Greens denounce in the other parties: in May 2013 one of their councillors, a former Lucas aide called Alex Phillips, contacted the leader of the Labour group on the council, Warren Morgan, to ask if he would support a move to replace the Green leader of the council, Jason Kitcat. Morgan chose to go public instead.

The Green Party has gathered support as the feeling grows that traditional politics in Britain has failed. On environmental issues, the feeling is that politics more generally has failed. The Greens have tried to respond to this mood with a brand of left-wing populism. But many of the voters the party is chasing don’t share its more radical ideas about the economy, while the changes the Greens believe are necessary to save us from our environmental predicament have barely filtered through to the electorate at all. The weak environmentalism that most people subscribe to – a mixture of technological change, renewable energy and recycling – is on the classic Green view only a little better than business as usual. Popular environmental campaigns like the Guardian’s Keep It in the Ground, which calls on the world’s two biggest charitable funds – the Bill and Melinda Gates Foundation and the Wellcome Trust – to divest from fossil fuel companies, represent an attempt to bring about change by circumventing politics. ‘The divestment campaign is not arguing for an end of all fossil fuel use starting tomorrow,’ the Guardian states. ‘Instead it is arguing that the burning of fossil fuels at increasing rates is driving global warming, which is the actual threat to modern civilisation.’ The trouble for the Greens is that they really would like to see the end of modern civilisation – as we know it. But you can only say that if you really are an anti-party party, and if there’s one thing the Greens are trying to be during this election campaign, it’s a party party.