Questions of leadership within the Green Party of England and Wales had already surfaced among senior figures before the party's leader fell short in the Holborn and St Pancras by-election, a contest called after former prime minister Sir Keir Starmer stepped down from his parliamentary seat.
Polanski told members he was prepared to continue leading the party, while making clear that any final decision on his position rested with the Green membership. A leadership vote pencilled in for next year would give Green Party members the final say on whether Polanski remains at the helm, he indicated.
When asked about his prospects in the next leadership contest, he told a news channel that the outcome would rest with the membership and with whatever process the party puts in place for the following summer's election. He noted that a large number of people had told him they had never felt greater pride in their Green Party membership, while also acknowledging the role of party leader as a demanding one — particularly within the Green Party — though he stated he had taken on that challenge willingly and remained fully prepared to carry on.
A conference vote the party leader did not attend passed a motion backing a resolution that would dissolve Israel and establish a single state under Palestinian governance in its place. His absence from the conference vote on the anti-Zionism motion was attributed to by-election campaigning commitments at the time. When asked whether he backed the motion, he indicated that his support would have extended to the amended version of it. He noted, however, that the substance of the motion was something he found himself in agreement with, even though it had not been amended.
On a broadcast of the Today programme, Mr Polanski — who is Jewish — was asked on multiple occasions whether Israel held a right to exist, and on each occasion he chose not to answer directly, instead putting forward the view that Israelis and Palestinians alike held equal rights within a democratic framework; separately, a point of disagreement was noted over whether the Green Party should be the body determining the region's future direction. When asked directly whether Israel had the right to exist, Polanski replied that Palestinians currently lacked equal rights, framing that as his answer to the question.
The seat itself went to Camden Council leader Sagal Abdi-Wali, who held the north London constituency for Labour. Her 45% vote share outpaced the Greens' 33%, producing a winning margin of 3,364 votes, though the count also captured a 13-point swing toward the Greens alongside a 22.4-percentage-point rise in their overall share of the poll.
Caroline Lucas, who previously led the party, argued that Mr Polanski ought to have attended and cast his vote, while Adrian Ramsay, a former co-leader, urged the party to refocus on its founding environmental mission. On Newsnight, Lucas — the first MP to represent the Green Party — told viewers that the coming days and weeks would reveal what lay ahead for Polanski. Drawing attention to Mr Polanski's absence from the vote on the anti-Zionism motion held that Sunday, she argued that his attendance and participation had both been expected of him.
Passage of the motion at the party's conference gives it the status of official policy — reached over the objections of Ms Lucas and four of the party's five MPs — though that standing carries no guarantee the measure will feature in any future manifesto.
The constituency of Holborn and St Pancras, created in 1983, spent its first three decades under Frank Dobson before passing to Sir Keir for a further eleven years, with Labour holding the seat throughout that entire span. Third place in the by-election went to the Conservative candidate Ewan Cameron, with Reform and the Liberal Democrats filling the positions directly behind him.
Abdi-Wali attributed the outcome to what she described as the borough's embrace of diversity. She expressed a wish that the moment might carry meaning for those who share her background, conveying that people like her deserve a place in such spaces and that their journeys are equally valid there. She noted that Camden's diversity reflected Britain's own, and went on to describe how residents across the borough had put effort into building neighbourhoods where difference was treated as something to embrace rather than avoid.