Ulez: Tories are missing a trick to claim victory against Sadiq Khan - analysis by Christopher Hope

Last night on GB News, presenter Nigel Farage urged transport secretary Mark Harper to use an apparent loophole in legislation to block the expansion.

He said the Transport Secretary could opt to cite the legislation which brought devolution to the capital in a bid to overrule Khan provided the “transport strategy (or any part of it) is inconsistent with national policies relating to transport” and the “inconsistency is detrimental to any area outside Greater London”.

The Bill added: "Where the Secretary of State gives the Mayor a direction under subsection (1) above, the Mayor shall revise the transport strategy in accordance with the direction."

On the face of it, as Farage made clear to GB News viewers, it appears that Harper can step in due to the issues facing people living around central London who will be forced to pay the bill if they are driving into the capital for work.

“What is without doubt is Khan’s policy of Ulez extension is detrimental - that’s the word - to every county bordering Greater London, whether it's Essex, or Kent, or Surrey, or round to Bedfordshire," Farage said.

“Wherever it is, it is [detrimental] because of the number of people living outside the Ulez area who’ve got their vans, who go into London to do their business, nurses who live outside of Greater London who’ve got cars who aren’t compliant."

Transport secretary Mark Harper is not budging though is not budging though. Harper's team insists that the expansion is up to Khan to reverse – and not a matter for HM Government.

His spokesman said last night: "It is for the Mayor to explain why he thinks it is fair to charge those with non-compliant vehicles £12.50 every time they drive."

Sources tell me that Harper has taken legal advice on whether he can intervene and has been told that he cannot.

This is why Susan Hall, the Tory mayoral candidate who want to depose Khan in May's City Hall election, is not pushing for the UK Government to step in.

Instead she says she will reverse the Ulez expansion the day after she hopes to replace Khan as London Mayor.

Hall told me today: "The Ulez expansion will be absolutely devastating to families, businesses and charities. I will stop the ULEZ expansion on day one of my Mayoralty, and take real action to reduce air pollution without taxing people."

But I wonder if Harper is missing a trick here by not stepping in? A legal challenge by Harper could delay the implementation of the expansion by some months, giving at least a chance that Hall can beat Khan next May and stop the policy in its tracks.

And it would demonstrate to voters that the Government is on the side of people who just want to get to work during this cost of living crisis. The surprise Tory victory in the by-election in Uxbridge and South Ruislip showed the political upside from fighting the Ulez expansion.

It would take political bravery to step in though, as it might mean over-ruling civil servants and incurring legal bills that would fall on the taxpayer.

But it would prove popular among voters who the Tory government wants to stand up for. It is a test for Harper, as we enter the run in to a major election year. What will he do?