London mayor Sadiq Khan has pleaded with Hertfordshire County Council to allow ULEZ signs in the county.

After council leader Cllr Richard Roberts outlined Hertfordshire's position in an open letter to Mr Khan on July 21, stating that “based on your current proposals” signs and cameras wouldn’t be allowed in Herts, the Labour mayor urged him to reconsider.

The mayor’s spokeswoman also called on Surrey County Council and Kent County Council to do the same.

She said: “Councils have a responsibility to ensure their residents and all motorists are aware of important changes that may impact drivers.

“By refusing to allow TfL to install ULEZ warning signs at key junctions, these councils outside London are not fulfilling their responsibility to ensure their residents and other motorists have all the information they need to avoid driving into the ULEZ inadvertently.

The Comet: Sadiq Khan has faced strong opposition over the expansion planSadiq Khan has faced strong opposition over the expansion plan (Image: PA)

“The mayor is urging these three county councils to put their politics aside and do what’s best for their residents and drivers.”

City Hall said TfL has offered to pay the full cost of installing and maintaining signs.

A spokesperson for Hertfordshire County Council said: “The expansion of the ULEZ zone by the Mayor of London to Hertfordshire’s borders will price some of the lowest paid in our county off the roads.

“No amount of signage will change the fact that our residents and businesses face a £12.50 penalty for travelling into the capital.

“It’s time for the mayor to do the right thing and pause the expansion before redrawing the boundary to start at public transport hubs in outer London.”

The Comet: Cllr Richard RobertsCllr Richard Roberts

In his letter Cllr Roberts also said Hertfordshire would ask that the scrappage scheme be extended to surrounding counties if the extension goes ahead.

Cllr Roberts said: “I would personally ask that you pause the expansion of the zone and look to redraw the zone boundary to align with outer London public transport hubs."

He ended the letter saying “we appreciate your overarching aim to improve air quality" and extended an offer for the mayor to meet the council and discuss achieving it.

The ULEZ will be extended to cover the whole of London from August 29.