Five local authorities, including Bromley and Bexley, must foot the bill of £730,941 after a failed legal challenge against the Mayor of London's ultra-low emission zone (ULEZ) plans.

The final sum includes £230,941 incurred by Hillingdon Council, which led the legal fight, plus £500,000 in legal costs to Transport for London (TfL). The London boroughs of Hillingdon, Bexley, Bromley, and Harrow, along with Surrey County Council, will each contribute £147,853.20.

Bromley Council's leader, Councillor Colin Smith, declared the spending "a sound and balanced risk" despite the loss, in efforts to protect residents and businesses from an ongoing tax rise of £3k per year.

Councillor Colin Smith, Leader of Bromley Council, said: “At a cost of a £1 to every home in the Borough once, in an effort to save tens of thousands of residents and business being taxed an additional £3k a year on an ongoing basis, the Council continues to regard the associated costs as a sound and balanced risk for Bromley residents as whole, and as such, stands foursquare behind its decision to join the Rebel Coalition of like-minded Boroughs on that basis.”

The Conservative-led councils, termed a "Rebel Coalition", launched legal action in February against expansion plans for the ULEZ by Labour Mayor Sadiq Khan but their case was dismissed.

He described the High Court judgment as a “landmark decision” and pledged to “do everything possible” to address “any concerns Londoners may have” about the scheme’s expansion on August 29.

Bromley Council's leader saw the court ruling as "bitter disappointment".

The local authorities’ lawyers said the mayor lacked the legal power to order the expansion of the zone by varying existing regulations and argued that there was an “unfair and unlawful” approach to collecting views on the plans.

The mayor’s legal team rejected the bid to quash his November 2022 decision to extend the ULEZ, arguing the move was “entirely lawful” and that “ample information” was provided for a “fair consultation”.

Giving a summary of his findings, the judge said: “I am satisfied that the mayor’s decision to expand the Ulez area by amendment of the present road charging scheme, rather than by making an entirely new … scheme, was within his powers.”

The judge added that, having “carefully considered” the consultation process, he was satisfied that enough information was given for people who wished to respond to provide “informed responses”.

Drivers of vehicles which do not meet minimum emissions standards are charged a £12.50 daily fee for entering the ULEZ zone.

Transport for London (TfL) says nine out of 10 cars seen driving in outer London on an average day comply with the ULEZ standards.

But figures obtained by the RAC show more than 690,000 licensed cars in the whole of London are likely to be non-compliant.

This does not take into account other types of vehicles or those which enter London from neighbouring counties.