London local elections 2026: Labour 'under siege' from Zack Polanski Greens but stays biggest party - new poll

Zack Polanski ’s Green Party is set to make “major gains” in traditional Labour strongholds in London, according to a new poll.

It put the Greens within two percentage points of Labour in three more boroughs, Lewisham, Lambeth and Islington.

Labour is still the biggest party in 21 boroughs.

But the Greens are in second place in 16 of them and putting Sir Keir Starmer’s party ‘under siege’’ in some of its traditional strongholds.

Luke Tryl, UK director at More in Common, said: “ Former Labour strongholds look set to see major Green gains with the potential the party controls or emerges as the largest party in a whole swathe of inner London.

“While the Greens advance in Labour’s heartlands, Reform looks set to do the same in outer-London boroughs such as Bexley that were previously safe for the Conservatives.

“Add in gains from Independents and it could well be that the electoral map of London we see on May 8th looks totally unrecognisable to what we have become used to.”
While the Greens and Reform are widely expected to make significant political inroads into London, the scale of their advances is yet unclear.

Many wards are also expected to be won by very small majorities, so their results are extremely difficult to predict in the new era of five-party politics.

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With the fragmentation of British politics, many more councils are also likely to fall to no overall control.

Reform UK appears on track to win Havering, with Nigel Farage having already told The Standard that his party will win the east Outer London borough.

Tory leader Kemi Badenoch has told of her optimism of winning back the former Conservative “crown jewel” councils of Westminster, Wandsworth and Barnet.

But the poll put the Conservatives behind Labour in all three of them and showed them leading in just five Outer London boroughs.

At least nine boroughs are on a knife edge, including Hillingdon in west London, with both Labour and the Tories on 26%.

The Greens are up 10 points to 20%, Reform up six to 15% and the Liberal Democrats up three to 14%.

In 2022, the last time the London borough contests were fought, Labour won more than 40% of the vote in 21 councils.

But now it is not breaking this threshold in any borough, the closest being Camden at 39.8%.

The Lib Dems are trailing Labour by 28% to 23% in their target borough of Merton, south west London.

Many voters only decide who to back just before polling day and the survey showed a fifth of Londoners are still undecided.

MRP polls are based on large-scale polling of sections of society and extrapolating to get constituency or council level results.

* More in Common interviewed 2,646 Londoners between April 7 and 29.