The quietly impressive performance by the Green Party at last week’s local elections might not have the Liberal Democrats shaking in their boots publicly, but the Party’s strong local showing will have some in the Lib Dem ranks quietly considering whether their reign as Britain’s third party might be under threat.

Co-leader Jonathan Bartley was quick to assert “We’re staking the claim to become England’s third party.” Though the Greens are nowhere near matching their rival’s significant representation in local government, results suggested that perhaps voters have finally come to see the party as a credible electoral force, showing a vote for the Greens should no longer be dismissed as a wasted vote.

Bartley and his co-leader Siân Berry’s claims are not without evidence. They won 88 more seats, compared to the Lib Dem’s modest increase of seven. Most impressive was their performance in Bristol, where they more than doubled their seats on the city council and gave incumbent Labour Mayor Marvin Rees a run for his money.

The key for the Greens ahead is whether they can translate momentum at a local level into national success. Caroline Lucas has been the Party’s only Westminster MP since winning Brighton Pavilion in 2010. Employing a tried and tested Lib Dem strategy, it’s thought that in the lead up to the next General Election they’ll target a handful of Westminster constituencies by promoting candidates as local champions.

One seat they have their eye on is Bristol West – currently held by Labour’s Thangam Debbonaire with a majority of 28,219 – but given their success in the city, they now believe they could be in with a chance.

But what’s behind the surge? Increasing recognition amongst the electorate that we’re facing a climate crisis has undoubtedly driven voters their way. It also speaks to a splintering of the Left’s vote – disillusionment with the stumbling Liberal Democrats, whilst also feeling that Labour under Keir Starmer is not a natural political home. It’s clear that there’s an increasing electoral coalition of liberal graduates and professionals who, should they have the means and the will, the Greens could woo.

Academic Matthew Goodwin has suggested that the UK could be going in the same direction as European neighbours, such as Germany, where cosmopolitan parties are eclipsing the old centre-left. Whilst election guru Sir John Curtice suggests though not a seismic shift, it could be a notable one, saying “these local elections appear to confirm that the Greens are now able to win a non-trivial proportion of the vote”.

Once dismissed as a bunch of sandal-wearing, vegetarian hippies, it would seem the Greens’ electoral fortunes could be on the precipice of change. Growing in confidence and more attuned to their public image, with a widely accepted message on climate change, they’re now mainstream. But Green success could come at a cost for the Left, further splitting Labour’s vote in such a way as to ensure the Conservative’s electoral victory for the foreseeable future.