Last week he backed drivers in their call for the penalties to be waived.

The affected drivers face the prospect of accepting the penalty notices and points or challenging the penalties in court, Mr Smith added.

Responding to calls to waive the penalties, a Met Police spokesperson said: “Our prosecutions team, which deals with speeding offences, has taken legal advice and the location of the 50mph sign would not have impacted the enforcement.”

The force contends that if a motorist was to have travelled through the section signed as 40mph at the maximum permitted speed of 40mph, then sped up to 50mph after seeing the now-removed 50mph sign, their average speed of the section covered by cameras would not have resulted in them being issued with a speeding ticket.

The spokesperson added that the offending 50mph sign was being investigated “as an attempt to pervert the course of justice”.

A social media group set up by those seeking to challenge the penalties has attracted more than 2,700 members.

Concerns have also been raised about the visibility of the legitimate 40mph signs installed by TfL.

Leon Funnell said he was given a £100 penalty charge and three points on his licence for driving at 70mph in the 40mph stretch, which happened because of “inadequate signage”.

He said the signage was too infrequent and that it was particularly difficult for drivers in the the right-hand lane to see the signs installed to the left of the road.