Meet the man who terrifies Andy Burnham – and is really running the UK today
Andy Burnham may have finally reached the top of British politics, but becoming Prime Minister does not mean having complete control over the political agenda.
The new Labour leader is facing pressure from Conservative leader Kemi Badenoch, Reform UK and a difficult economic situation. Yet one of the most interesting challenges is coming from further to his left.
That challenger is Zack Polanski.
The Green Party leader is preparing to contest the October 8 by-election in Holborn and St Pancras, the constituency formerly represented by Keir Starmer. Labour has selected Camden Council leader Sagal Abdi-Wali, while 15 candidates are standing in total.
Polanski is openly presenting the contest as an opportunity to put pressure on Labour from the left.
Whether he actually wins the seat is a question for voters. But his political influence does not depend entirely on becoming an MP.
His growing presence has created a strategic problem for Burnham: Labour must compete not only with parties to its right, but also with a Green Party seeking to attract voters who believe Labour has compromised on climate policy, housing, inequality and international affairs.
The by-election that has put the Greens under the microscope
Holborn and St Pancras is particularly important because of its history.
Starmer represented the constituency until he stepped down as an MP after leaving Downing Street. The resulting by-election takes place on October 8.
Polanski was formally selected by the Green Party on September 11. He has described himself as an underdog but said the Greens have “momentum” and can achieve what would be a significant result for the party.
Labour’s candidate is Sagal Abdi-Wali, a local political figure and former Camden council leader.
The contest has consequently become more than a routine parliamentary vacancy.
For Labour, it is a test of whether the party can retain support among voters who backed it previously but may now be attracted to a Green message.
For Polanski, it is an opportunity to turn national political visibility into parliamentary representation.
And for Burnham, it is a reminder that his Government’s left flank is now being contested.
Polanski is deliberately challenging Labour’s agenda
Polanski has made no secret of his political differences with Burnham.
After Burnham became Prime Minister in July, the Green leader said Labour would be judged on whether it addressed what he called the affordability, inequality and climate crises.
He criticised Burnham for appearing to offer continuity rather than a fundamental break with the previous Labour government.
The Green Party has subsequently focused heavily on rent controls, wealth taxation, public ownership, climate policy and opposition to new North Sea oil and gas development.
Those positions put Polanski in direct competition with Labour over voters who want a more left-wing economic and environmental programme.
The significance is not that every Labour voter agrees with the Greens.
It is that Burnham cannot simply assume that voters who reject Conservative or Reform policies will automatically remain loyal to Labour.
A challenger does not need to replace the governing party nationally to affect its strategy. In a closely contested political environment, even the possibility of losing support in particular constituencies can influence where a government directs its attention.
North Sea oil has become one of the clearest dividing lines
Energy policy provides one of the clearest examples.
Polanski has repeatedly attacked the Government over the possibility of approving further North Sea oil and gas projects.
In August, he criticised Burnham over the Jackdaw gas field and argued that approving new drilling would conflict with Labour’s previous commitment on North Sea licensing.
He has also explicitly mentioned Rosebank, calling on Burnham to maintain opposition to new oil and gas drilling.
The issue is politically complicated because there are competing arguments.
Supporters of continued domestic production point to energy security, jobs, tax revenues and reduced reliance on imports.
Environmental campaigners argue that expanding fossil-fuel production conflicts with climate objectives and that Britain should accelerate investment in renewable energy.
The debate has become particularly relevant as the Government considers its energy strategy.
Scottish Labour’s newly elected leader Michael Marra has recently backed both Rosebank and Jackdaw, arguing that the projects are important to Scotland’s economy and jobs.
That demonstrates the tension within Labour itself.
Burnham must balance climate commitments against arguments about employment, industrial capacity and energy security.
Polanski’s pressure is not confined to climate policy
The Green leader has also taken a strong position on Britain’s foreign policy.
In July, Polanski called on Burnham to end UK military support for Israel and take further action over the war in Gaza.
The issue is politically sensitive because Labour has a substantial Muslim electorate while also facing pressure from other sections of its voter base over Israel and antisemitism.
More recently, Polanski has also intervened in the debate over Israel and Zionism within the Green Party itself. The party is preparing to debate a controversial motion at its conference that would define Zionism as racism, with amendments proposed and concerns reported about its potential impact on Jewish members.
This illustrates the political territory Polanski is attempting to occupy: a strongly left-wing platform combining economic redistribution, climate action and a more confrontational foreign-policy position.
Defence creates another problem for Burnham
The Government’s defence policy has provided another area of criticism.
At Prime Minister’s Questions on September 9, Burnham refused to commit to increasing defence spending to 3 per cent of GDP by 2030.
Instead, he argued that the Government needed a fully funded plan and said strong national security depended on having adequate social security as well.
Conservative leader Kemi Badenoch has attacked that position, arguing that the Government should move faster on defence spending in response to the deteriorating security environment in Europe.
The dispute demonstrates that Burnham is being pulled from both directions.
The Conservatives argue that he is not moving quickly enough on defence.
The Greens are pushing him towards stronger climate and social policies.
Reform is competing for voters on immigration and national sovereignty.
And the Government has limited financial room to satisfy all of these demands simultaneously.
The economy makes the balancing act harder
Burnham’s political calculations are also constrained by the economy.
Inflation reached 3.1 per cent in August, while borrowing costs have risen sharply ahead of John Healey’s October 28 Budget. Reuters reported that the 30-year gilt yield had reached its highest level since 1998.
That leaves the Chancellor with difficult choices.
The Government cannot simply promise every policy demanded by its supporters without explaining how those commitments will be financed.
This is particularly important for the Greens, whose programme includes major increases in public investment and stronger intervention in areas such as housing and energy.
Burnham therefore faces a familiar problem for governments on the left: how to satisfy demands for greater public spending while maintaining fiscal credibility.
Polanski can campaign for more ambitious policies from outside government.
Burnham has to find the money to implement them.
Is Polanski really “running” government policy?
That is the central claim behind the dramatic headline.
There is currently no evidence that Polanski literally controls Burnham’s Government or that individual government decisions are being made at his instruction.
Indeed, the available evidence shows something more complicated.
Polanski is publicly applying pressure on issues where Labour’s position is vulnerable to criticism from its left. The Green Party has then used those issues to argue that Burnham should go further.
That is political pressure, not government control.
Whether that pressure changes policy is a separate question.
The timing of decisions can also become politically significant. For example, the Government’s approach to North Sea drilling is being watched closely by both environmental campaigners and Labour’s industrial constituencies.
But establishing that a particular policy was delayed specifically because of the Greens would require evidence of the Government’s internal decision-making that is not publicly available.
The October by-election will provide a test
The Holborn and St Pancras contest will therefore be closely watched.
It will not determine the national government.
It will not automatically establish that the Greens have replaced Labour as the dominant force on the left.
But it can provide evidence about the strength of Green support in a constituency where Labour has historically been competitive and where political attitudes have shifted in recent elections.
Reuters noted that the Greens won more than 10 per cent of the vote in the constituency in the 2024 general election, while an independent candidate campaigning around opposition to Israel’s actions in Gaza won around 19 per cent. That independent candidate is not standing in the by-election.
That background helps explain why the contest has attracted attention.
The Green Party sees an opportunity to consolidate voters who previously supported other candidates on the left.
Labour, meanwhile, has selected a local candidate with strong community connections and is attempting to defend the seat.
Burnham’s bigger challenge
The broader political question is whether Burnham can maintain a coalition wide enough to govern effectively.
He needs to appeal to traditional Labour voters while also attracting voters who want economic growth and stronger public services.
He needs to address climate concerns without ignoring energy security.
He needs to increase defence spending while protecting other public spending commitments.
He needs to manage Britain’s relationship with the United States and Europe while responding to domestic political pressure over foreign policy.
And he needs to do all of that while facing a difficult fiscal environment.
Polanski’s emergence adds another variable.
The Green leader does not have to become Prime Minister to influence Labour’s political calculations. If the Greens demonstrate that they can attract significant numbers of Labour-leaning voters, Labour has an incentive to pay closer attention to issues where those voters are most dissatisfied.
But there is an important limit.
A government cannot simply adopt every demand made by a rival party. Doing so could alienate other parts of its electoral coalition, business groups, trade unions, voters concerned about defence, or those who prioritise fiscal restraint.
That is why the claim that Polanski is “really running the UK” should be understood as political commentary rather than a literal description of how government operates.
The real test comes after the headlines
The October 8 by-election may tell Burnham something about the political mood in one London constituency.
The more important test will come afterwards.
If Labour changes policy, the question will be whether those changes are driven by economic evidence, national security considerations, environmental commitments, electoral calculations or some combination of all four.
If the Government proceeds with policies opposed by the Greens, Polanski will have an opportunity to argue that Labour has ignored the pressure coming from its left.
If Burnham moves closer to Green positions, his opponents will be able to argue that the Greens have influenced the Government.
Either way, the political relationship between Labour and the Greens is becoming harder to ignore.
Polanski’s influence should therefore not be measured simply by whether he enters Parliament on October 8.
His real impact will be determined by whether he can persuade voters that there is a political space to Labour’s left — and whether Burnham believes that space is large enough to threaten his government’s support.
For now, one thing is clear: Andy Burnham may occupy Number 10, but he cannot dictate the political agenda without responding to the forces gathering around him.
Zack Polanski is one of those forces.
Whether he becomes a serious parliamentary challenger or remains an influential voice outside Westminster, his campaign is forcing Labour to confront a question it would probably rather avoid: how far left can Burnham move without losing voters elsewhere?