LONDON — Zack Polanski promised to smash Britain’s two-party political system — but his campaign for a U.K. parliamentary seat has leaned heavily on the idea that he can keep the existing prime minister honest.
POLITICO analysis of the online battleground in the Holborn and St. Pancras by-election – which takes place Thursday — shows the Green leader has been pitching himself as a protest vote for Labour-backing constituents in the London seat, which has been held by Labour since its creation in 1983.
The party has spent nearly £5,000 pushing ads on Meta’s platforms, which include Facebook and Instagram, promising that a Green win would help “keep the government in check.”
In one campaign video, Polanski takes credit for a series of Labour U-turns on their “most unpopular policies” over the last 12 months. A victory in the seat, he claims, would add further pressure on Prime Minister Andy Burnham to listen to the Greens, rather than “Nigel Farage, Donald Trump, or their corporate donors.”
An additional £7,000 has been spent by the party promoting graphics of recent newspaper headlines it thinks demonstrate the influence it holds over Burnham’s Labour government — including a Guardian story flagging a possible delay on North Sea gas field decisions until after the by-election.
“When Zack Polanski speaks, Labour listens. That is the power of the leader of the Green Party,” the accompanying ad copy states.
Building Brand Zack
The by-election marks Polanski’s first attempt to win a seat in the House of Commons.
The left-wing leader oversaw a rapid polling increase for the Greens after taking charge in September 2025, snatching a Labour safe seat in Gorton and Denton under former Labour Prime Minister Keir Starmer the following February.
But its polling momentum appears to have stalled since Labour switched to Burnham, and the party has also faced internal rows over anti-semitism.
The party has spent around £8,000 on targeted ads highlighting endorsements for Polanski from local residents, including former independent candidates and NHS workers.
And at least £500 of that has been spent promoting effusive praise of the Green leader from his own local hairdresser.
Alongside a picture of the pair hugging, barber Rami is quoted saying: “I’ve been cutting Zack’s hair for years. When you chat to him you can tell how much he really cares.”
A significant number of the showcased endorsements come from former Labour backers and members as Polanski seeks to convince voters that Burnham’s majority — and the mid-term timing of the contest — means they can register a protest vote in the symbolic seat previously held by Starmer.
One standalone advert features former Labour member Gopa, who says: “We all know there will still be a Labour government whoever wins, so I’m excited for a Green candidate who will listen to us and help push Labour to do better.”
Other endorsements include a Labour member of three decades who says she is now backing Polanski after her former party “lost its way and let me down.” Ex-Labour councillor Naser says he’s switched his allegiance to “keep the pressure on, and keep Labour in check.”
The Labour pitch
By contrast, Labour candidate Sagal Abdi-Wali has kept her campaign local.
She has spent more than £21,000 with Meta promoting dozens of slick cinematic clips and polished graphics pitching herself as a “local champion.”
Supported by Labour’s well-oiled digital team, Abdi-Wali’s online campaign focuses heavily on her experience of arriving in the area as a child refugee, and her subsequent career as a local councillor.
Labour has also pumped more than £20,000 into Google’s ad program. The majority of that sum was spent on bitesize YouTube ads, with the remainder spent on buying up sponsored Google search results in an attempt to grab the attention of voters hunting for information about the contest.
Also running
Britain’s hard-right Restore Britain has also been making a pitch to voters in Holborn and St Pancras — while openly admitting it has no chance of winning in “one of the most left-wing seats in Britain.”
Rupert Lowe’s party has spent around £30,000 on Meta ads positioning itself as a “genuine patriotic alternative” to Nigel Farage’s Reform UK — which has not spent significant cash in the contest.
Restore’s spending included £1,500 promoting a “quiz” comparing comments from Reform politicians with Restore’s more hard-line agenda. A further £2,000 went on promoting a graphic of the “ten reasons” why voters should support it.
That list includes removing “millions of foreign nationals who hate who we are,” a promise to “reverse the Islamification” of London, deport “foreign tramps who ruin our city” and force “healthy” benefit claimants to clean graffiti and pick litter.
In a further attempt to present his insurgent party as a credible alternative to Reform or the Conservatives, Lowe’s paid online content repeatedly describes the by-election as a “free hit” for right-wing voters to “vote with your heart.”
“They don’t want the capital reformed, or conserved,” one paid ad states. “They want London restored.”