Sian Berry is resigning as a London councillor in order to focus on her campaign to be elected in Brighton Pavilion.

Ms Berry, who was selected as the Green candidate to replace Caroline Lucas to keep the party’s only seat in parliament at the next general election, has served as a councillor for Highgate ward in Camden since 2014.

However, in a letter to Camden New Journal, she said she would be leaving her role as it is “necessary to put the time needed into winning Brighton Pavilion and [do] justice to the legacy of Caroline Lucas”.

She said: “Representing the people of Highgate and being an independently minded Green voice on this council has been the most rewarding and instructive job of my whole life.”

Ms Berry was the only Green councillor on Camden Borough Council.

Her resignation triggers a by-election in the Highgate ward, where voters have elected at least one Green councillor at every local election since 2006.

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She said that during her time as a councillor over the last nine years she has been “acutely aware of my responsibility not only to represent Highgate residents, but also the one in eight voters across the wider borough who put their crosses by the Greens”.

Ms Berry moved to Brighton after being selected as the Green candidate earlier this year.

At the Green Party conference in the city this month, which paid tribute to Caroline Lucas as she prepares to stand down as an MP at the next election, Ms Berry said she was “lucky and proud” to call Brighton “home”.

Speaking to The Argus, she said: “Moving house is a big thing and I’m settling into my new flat now and meeting lots of people on the doorstep every week.”

Voters are expected to go to the polls for the general election sometime next year.