While Labour has claimed that victory in two by-elections is another step towards taking the keys to Downing Street, it was a victory that also exposed a flaw in its policy on cutting harmful emissions.

And it is a weakness that could, if not addressed, cost it vital support in key target seats in Kent.

After a period of relative stability in which it has focused relentlessly on Sir Keir Starmer’s five missions, there has been rather a bumpier ride on ULEZ and plans by the Labour Mayor Sadiq Khan to widen the area of the policy to greater London.

The extension of the Ultra Low Emissions Zone has a direct impact on those parts of Kent that adjoin London; and a clutch of target seats are in range where drivers could face having to pay a hefty daily charge if they cross over into the capital.

It was no surprise that the issue was put front and centre of the Conservatives’ campaign in Uxbridge and Ruislip, the seat of the former PM Boris Johnson. It worked pretty effectively: the party won, albeit by a vastly reduced majority.

Party leader Sir Keir Starmer made the right call in identifying the issue as the one that cost it victory but now needs to engineer a solution that does not look like an abject climbdown.

The London Mayor has also accepted it was a factor and has indicated he is in listening mode; probably after a dressing down from the leader.

It is something the party leadership needs to do something about sooner rather than later.

And it also needs to acknowledge that voters who rejected the policy did so because it was wrapped up in the cost-of-living crisis; not necessarily because they did not accept that tackling pollution and curbing emissions was important.

One Labour source said the fault lay firmly at the Mayor’s door, saying in fairly robust terms that “he made a balls-up”.

They added: “A new electric family car costs about £50,000 - I don’t know who has the cash for that. And then there’s the infrastructure costs like charging points - and there’s not enough.”

It is concerns like that that make a prolonged period of inaction unhelpful; neither will simply putting a decision off until after the general election.