Local government minister Brandon Lewis has pledged to investigate whether local authorities are illegally setting targets for the number of parking tickets issued by traffic wardens.
Following an investigation, the BBC's Inside Out programme alleges that three London boroughs - Lambeth, Bromley and Hackney - are setting targets or offering incentives.
Bromley, it says, is offering financial bonuses to private contractor Vinci for every penalty charge notice issued over a baseline number of 72,000. Meanwhile, says the BBC, Lambeth has stipulated in its contract with NSL (formerly NCP) that it requires at least 205,000 penalty notices to be issued every year.
And Hackney contractor APCOA is said to band individual wardens on the basis of the number of tickets they issue per hour, with the council stipulating that no more than ten percent can fall below 'band two'.
However, such clauses appear to be prohibited by the government's Operational Guidance to Local Authorities: Parking Policy and Enforcement.
"An enforcement authority should base performance measures and rewards or penalties, wherever
possible, on outcomes rather than outputs. Performance and rewards/penalties should never be based on the number of [penalty charge notices] PCNs, immobilisations or removals," this reads.
In other words, if incentives are to be offered, they should be on the basis of falling numbers of offences - never on the number of penalties issued.
The three councils have all denied setting targets, with Lambeth saying its figures are for guidance only, Hackney that it's removed the offending paragraph from its contract and Bromley denying that it's ever set targets.
But Brandon Lewis says he's concerned about the contracts, and has promised to ask lawyers at the Department for Communities and Local Government to examine them and establish whether they can be challenged in court.
"These look like entirely the wrong kind of contract, motivating and encouraging the staff to go out and penalise people - and they only get paid well if they penalise somebody," he says. "That's the wrong way to run the structure."
All three councils have made hefty profits from parking charges in the last year. Bromley pulled in £5.7 million, Hackney £7.9 million and Lambeth £12 million - more than twice as much as in the previous year.
Hackney Council was also recently accused of using CCTV cameras to gather evidence of illegal parking, without alerting motorists to the cameras as required. After an investigation, it cancelled the fixed penalty notices issued on the basis of camera evidence.
Campaigners say that local authorities are going too far in trying to raise revenue through parking notices.
"We are not remotely surprised by this," says Rupert Lipton, managing director of the National Motorists' Action Group. "Many councils have completely forgotten that their primary duty is to serve their residents. Instead they cynically use their parking departments to generate revenue – although they know that they must deny this as it is unlawful. "