An incorrect speed sign placed on a busy road where thousands of motorists have been fined is being treated as an “attempt to pervert the course of justice”.

Transport for London (TfL) has temporarily changed the speed limit on part of the A20, between Crittals Corner, in Sidcup, and the Swanley Interchange, from 50mph to 40mph.

Thousands of people are thought to have received notices of intended prosecution (NIPs) for speeding.

Many say they were unaware the limit had changed and others pointed to conflicting signs, with at least one 50mph still being up, as of January 24.

It is thought the incorrect sign, on the approach to the Swanley bypass BP garage, was placed by a third party and has since been removed and replaced with the correct 40mph one.

The Met Police has confirmed it is investigating this as an attempt to pervert the course of justice.

Many motorists driving at 40mph said they sped up when they saw the 50mph sign only to be caught by the cameras.

They have now received NIPs for exceeding the new 40mph limit.

KentOnline has submitted a Freedom of Information (FOI) request to the Met Police to see how many fines have been issued since the new measures came in.

Director of motoring solicitors Patterson Law, Dominic Smith, has been advising people who have received fines on this stretch of road.

He believes around 60,000 NIPs will have been sent yet said many may have a case in court if they can prove the signs were “confusing”.

Speaking to KentOnline he said the number of fines was “unprecedented”. He added: “I have never seen anything like this before.

“There have been thousands of people caught. They cannot all be wrong.

“People are at risk of losing their jobs and homes because of this. It is just not fair.”

However, a Met spokesperson said its prosecution team, which deals with speeding offences, had taken legal advice and where the 50mph sign was “would not have impacted the enforcement of the 40mph average speed limit”.

It is understood that if someone had travelled at 40mph, then sped up to 50mph after seeing the now-removed sign, their average speed of the section covered by cameras would not have resulted in a speeding ticket.

In response, Mr Smith added: “I think that is a ludicrous decision but one that does not surprise me.”

Motorist Serena Brooks, of Kemsing, near Sevenoaks, who has received two NIPs, thinks the lack of communication and clarity over the changes has caused a lot of issues for drivers.

The 43-year-old said previously: “There must be so many people who are stressed, who have not been able to sleep or eat over the NIPs.

“People are going to lose their jobs and homes. Most people have a clean licence and now they are at risk of losing it over this.”

The temporary changes have been introduced along the A20 Sidcup Road due to safety concerns over surface water flooding.

The speed reduction is an emergency order meaning no formal consultation was required.

A TfL spokesperson added: “Major work is required to put in place permanent measures to tackle flooding here and we are working to do this as soon as possible. We plan to begin construction work on these measures in May.”

Flooding has caused aquaplaning, with seven crashes being recorded between 2019 and 2022 due to a loss of control.

It has also caused multiple vehicles to crash into the BP forecourt and petrol pumps along the Swanley Bypass causing hundreds of thousands of pounds of damage.

The speed limit change will be in place until permanent drainage works can be completed.

A Facebook page has been set up for affected drivers and amassed more than 11,000 members who have been sent NIPs.

Kent MPs Laura Trott, Gareth Johnson, Kelly Tolhurst, Tracey Crouch, Damian Collins, Damian Green, and Adam Holloway have also written to the Mayor of London Sadiq Khan and the commissioner of TfL.

Alongside their London colleagues, they have raised their "serious concerns" about the new measures.

They have requested that the fines, which were issued by the Met Police, and license points be cancelled for drivers travelling 50mph and under to clear up the “mess”.