Other parties will have to come to us, says co-leader, as Greens enjoy rise in electoral fortunes

The buoyant Green party would not automatically seek out a so-called progressive alliance with bigger left-leaning parties if there were a snap general election, the party’s co-leaders have said.

At the start of a spring conference where the Green faithful will celebrate successful local and European elections, as well as national polling putting the party’s support at up to 9%, Jonathan Bartley and Siân Berry said it would be up to Labour or the Liberal Democrats to pursue the Greens.

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Berry, who became co-leader with Bartley last September, taking over from Caroline Lucas, said: “There’s a very good case in many constituencies for us to be seen as being in the strongest position to beat the Brexit party.

“The other parties would have to come to us, and we wouldn’t be giving anything away in talks. It isn’t our job this time to start anything. We already did that.”

Overtures by the Greens to the Lib Dems and Labour before the 2017 election to avoid splitting the anti-Conservative vote through constituency-based pacts came to nothing, and a similar idea for the European elections last month fell foul of what Bartley called “game playing”.

He said of any future deal: “On any issue where there’s common ground, we’re always willing to have a conversation. But at the same time, it’s going to have to be a very robust conversation. We are offering something very different.”

The party has had a successful few months, thanks to a combination of some remain-minded supporters abandoning Labour, greater public awareness of environmental issues following the Extinction Rebellion protests, and the spread of ideas the party has championed, such as a four-day working week and a “green new deal”.

In the local elections in May, the Greens were the biggest proportional gainers of the national parties, winning 194 new councillors. Later that month, the party beat the Conservatives in the European elections, taking almost 12% of the vote.

The co-leaders said the surge was also the result of many years of patient organising at a local level, building up what Bartley called a “network of field organisers”.

Berry said: “When the local election results came in, every time it was, ‘Yes, I’ve been there, Jonathan’s been there, I recognise those people, I know why they won.’ It wasn’t a protest vote, a flash in the pan, a single issue. It was our hard work all year round that’s leading to the results.”

The conference this weekend in Scarborough will feature a celebration of recent successes, but also new policy proposals, including a formal endorsement of the global climate strike – a planned series of protests in September – spearheaded by the teenage Swedish activist Greta Thunberg.

Other initiatives will be new ways to measure the strength of the economy and transport policies based around the £50bn-plus saved by scrapping HS2.

Bartley said: “We think it’s time to pull the plug on the project and put that money into the rail revolution that we need – cross-country and city links, getting more freight on to rail, electrifying lines, plus new bus routes for rural communities.

“And to find an alternative to short-haul flights, to get people out of their cars. If we’re going to make this move to a zero-carbon economy, we’re going to have to think very differently about this infrastructure. And we’re the only party putting forward this programme.”

While much recent coverage of politics beyond the established parties has focused on the Brexit party – which is topping Westminster polls, in which the Greens are fifth – Berry and Bartley said the rise of Nigel Farage’s party presents an opportunity.

“We’re the antidote to the Brexit party,” Bartley said. “We’re the party that hasn’t compromised. And all the other parties have compromised.

“There’s an issue of trust. A lot of Labour voters came to us in the European elections because they were disappointed in Labour’s position on Brexit, and didn’t trust the Lib Dems because of their record.”

If some of these switching voters backed the Greens in the local and European elections, it could become a habit, he argued: “Just going back three months, we knew that this could happen, but we were in a very different position. And this is the nature of politics now, you just do not know what is round the corner.”