Green policies have never been more relevant or urgently needed given the energy and cost of living crises, the party’s co-leaders have said before a conference seen as a crucial chance to influence the UK’s political direction. Carla Denyer and Adrian Ramsay will use the Greens’ annual get-together in Harrogate from Friday to unveil details of a wealth tax that would pay for policies, including insulating millions of homes. Ramsay said in an interview with the Guardian that the surging cost of energy and associated pressures on households highlighted the close link between environmental and social justice issues, one he said his party had been a pioneer in stressing. “The question is how soon the political establishment will catch up with what Greens have been arguing for,” he said. “We’ve had heatwaves. We’ve got a cost of living crisis driven mainly by energy. These are issues that Greens have been warning about for decades, and we now need the action to address them. “It is a crucial time. The need for Green ideas has never been greater. We need to make sure other parties that are making broad promises actually follow through in terms of what is delivered.” Insulation would play a key role in this, he said. “The cheapest bills are the bills people don’t have to pay … The Conservatives are taking us in the wrong direction.” Ramsay, a former deputy leader who was a councillor in Norwich, and Denyer, a councillor in Bristol, go into the conference with the Greens in England and Wales polling at up to 8%, but with other parties seeming to adopttheir ideas. Denyer said she had sceptically observed the recently concluded Labour conference, which took place under the slogan of “a fairer, greener future” and featured the unveiling of series of policies on green energy. Most of them, Denyer argued, were not new. “It’s pretty much what they were saying before, and it is not at the scale that is required to to reach the carbon reduction targets we need to reach.” Ramsay said: “Labour have copied our slogan but haven’t copied the policies that need to go with it.” In taking over a year ago from the departing leadership duo of Sian Berry and Jonathan Bartley, Denyer and Ramsay were seen as offering a model for the Greens based primarily around electoral goals, in contrast to their main rivals, Amelia Womack and Tamsin Omond, who had closer ties to direct action groups such as Extinction Rebellion. In the first major test of their tenure, at May’s local elections, the Greens made significant gains, taking seats both from Labour, especially in towns and cities, and from the Conservatives. Denyer said the party had recorded an increase in new members who had left Labour seeking more radical policies, not just on green issues but areas such as a wealth tax and wider public ownership of utilities, while some Tory voters seem put off by Liz Truss’s apparent intention to roll back environmental protections that originated with the EU. “It’s really interesting to see people like the RSPB explicitly saying they’re angry with the government for what they’re doing,” she said. While the number of Green councillors has surged, the first-past-the-post electoral system means the party is stuck on one MP, Caroline Lucas in Brighton. Ramsay and Denyer are both targeting seats, with the former, depending on whether boundary changes are implemented, doing so in Suffolk. Denyer will again fight Bristol West, where she came a distant second to Labour in 2019. Another element of the Labour conference noted keenly by the co-leaders was delegates’ decision to back a proportional electoral system, although Keir Starmer’s team do not plan to abide by the vote. “It’s certainly very positive that Labour party members have supported proportional representation, and about time too,” Denyer said. “I think the UK Labour party is the only social democratic party in Europe that doesn’t support proportional representation.” It was, however, depressing that Starmer seemed so resistant to changing the system, Denyer said, recalling that one Green colleague who had left Labour described them as “a battle between what the people actually want and the party, who feel their job is to stop it happening, or at least to slow it down”. Labour was “stuck in a politics that is decades old”, Ramsay said. “If you look at countries around Europe, parties work together, they work cooperatively to make an impact. And there are so many countries, including Scotland, where Greens are in government as part of a progressive coalition.”