Sir Keir Starmer’s party had been the favourites to win the seat for many weeks, but many voters in the outer London borough took the opportunity to vote against Labour because of the unpopularity of the Ultra Low Emission Zone (ULEZ) around the city.

The Conservatives won 13,965 votes, narrowly ahead of Labour's 13,470, meaning the majority is 495, slashed from 7,210.

The new Tory MP Steve Tuckwell made clear that “Sadiq Khan has lost Labour this election and we know that it was his damaging and costly ULEZ policy that lost them this election”.

Ballots are counted at Queensmead Sports Centre in South Ruislip, west London after voting at the poll stations closed in the Uxbridge and South Ruislip by-election, called following the resignation of former prime minister Boris Johnson. Picture date: Thursday July 20, 2023. PA Photo. See PA story POLITICS ByElections. Photo credit should read: Jordan Pettitt/PA Wire

In a blow to the Labour leader, Rishi Sunak was able to avoid the prospect of becoming the first prime minister since 1968 to lose three by-elections on the same day.

London mayor Sadiq Khan’s policy of expanding the Ulez low emission zone to outer boroughs – including Uxbridge and South Ruislip – has been blamed by many for the party’s failure to take the seat.

Labour candidate Danny Beales had distanced himself from the policy, saying it was “not the right time” to expand the £12.50 daily charge for cars which fail to meet emissions standards.

Shadow justice secretary Steve Reed said: “Everyone wants to see clean air. But for some people, I think, given the chaos that there is in the economy, because the Conservatives have crashed it and the cost-of-living crisis that they fuelled, that this is the wrong time to introduce a charge for Ulez.”

Tories hold on to Uxbridge in by-election upset for Labour