ULEZ: reports Rishi Sunak considered using government powers to block controversial London expansion

Reports have emerged that Rishi Sunak sought advice on using its legal powers to block London's controversial ULEZ expansion, but backed down after lawyers told them it would not hold up in court.

Despite opposition and a failed High Court challenge, from next Tuesday (29 August) the ULEZ - or ultra low emission zone - expansion will come into force across all of Greater London's boroughs, meaning people driving vehicles considered to high-polluting will face daily charges of £12.50.

The spotlight has recently returned to the controversy around the ULEZ expansion, and to clean air policies in general, after Labour's narrow Uxbridge by-election loss to the Conservatives last month was attributed to it - which has lead to other green policies across both parties facing increased scrutiny.

The Telegraph reports that cabinet ministers had been considering using a little-known legal power in the 1999 Greater London Authority Act.

This would allow them to overrule London Mayor Sadiq Khan's policy if it was found to be "inconsistent with national policies" - or was "detrimental to any area outside Greater London".

However, the paper said it understood that formal legal advice was sought, which concluded that the move would fail if challenged in court.

The government's lawyers said given that the UK Government itself was promoting moving to reduce air pollution air pollution, ULEZ would not be found “inconsistent” with the government’s stance. The Telegraph said Downing Street elected to look at other options instead.

It is unknown as of yet what these options could be, but Rishi Sunak - who has declared himself pro-motorist - has been urged by Conservatives to find an answer.

A spokesperson for the London Mayor told the BBC the government would only have been able to use this power "after changing national policy to prevent all cities charging drivers based on their emissions".

"Ministers have directed numerous UK cities to introduce clean air zones, and the government is under clear legal obligations to tackle air pollution," they added. "The mayor has received no suggestion from government that they have any intention to renege on these commitments."

Sadiq Khan Tweeted in response that instead of attacking the powers of devolved mayors, Sunak should "focus on working with us, and fulfilling his legal obligation to tackle the UK’s toxic air pollution".

"Birmingham, Bath, Sheffield and Tyneside all have clean air zones, funded by the [government]," he added. "Does the PM want people there to breathe dirty air too? Or just London?"

Research by local authorities suggest that while ULEZ and CAZ policies are no silver bullet, they do make a difference to both nitrogen dioxide pollution - linked with adverse effects on human health - and carbon emissions.