The Tories claim the scheme is part of Labour's "war on motorists".
John Kay pointed out to Mark Harper that the scheme was first introduced by Boris Johnson.
London's mayor has announced a new scheme following the fallout from the Uxbridge by-election.
Sources close to the London mayor now say he is "listening" in the wake of Labour's defeat in Uxbridge.
Danny Beales said it had "cut us off at the knees" as the Tories clung on by just 495 votes.
Angela Rayner blamed the scheme for the Tory win but the mayor insisted it is "necessary to save the lives of young and vulnerable Londoners".
Tensions between the London mayor and Keir Starmer are set to increase after the Tory victory.
The former prime minister used to say the Ultra Low Emission Zone was "an essential measure to help improve air quality".