The Green Party’s former co-leader Sian Berry has resigned from her role on the London Assembly, just three days after winning re-election.

Her departure from City Hall means that the party’s mayoral candidate, Zoe Garbett, will take her place, without the need for a by-election.

Ms Berry - a former Highgate councillor - is running to replace Caroline Lucas as Green MP for Brighton Pavilion, though she had previously told the Local Democracy Reporting Service that she would “keep representing the people of London” until the general election – and would only resign if she successfully became an MP.

Commenting on Tuesday, she said: “Zoë has shown how much of a difference she will make in City Hall, listening to Londoners and bringing their voices into the political debate.

“That’s why she needs to be in this job as soon as possible. She is already a brilliant councillor and will be a brilliant assembly member for Londoners.”

Ms Berry had served on the Assembly since 2016, and was the Green mayoral candidate in 2008, 2016 and 2021.

Like her fellow Green colleagues, she was re-elected to City Hall on Saturday as a London-wide assembly member, as part of a list of candidates put up by the party.

The Greens received 11.6 per cent of the vote on that ballot, which was only enough to get their top three candidates elected as assembly members. Ms Garbett was placed fourth on the list, meaning that she narrowly missed out on joining them.

But Ms Berry’s resignation means that Ms Garbett is automatically allowed to take her place, with no by-election required.

The same procedure has been used in the past when assembly members like David Lammy and Kemi Badenoch – both now senior MPs – decided to leave the Assembly mid-term, as they won seats in Parliament.

Ms Garbett said: “I am excited to join the Assembly and get to work for Londoners. There is so much to do to improve the quality of our lives in London, stand up for people on the margins and hold the mayor to account.”

As mayoral candidate, Ms Garbett received 5.8 per cent of the vote last week. Having come third in the previous three mayoral elections, the Green Party slipped into fourth place last week, coming behind the Liberal Democrats by just 70 votes.

Labour’s Sadiq Khan was re-elected with 43.8 per cent of the vote, while his Tory rival Susan Hall took 32.7 per cent.