Newham Council in London has been told it must refund around £347,000 to drivers in illegally-issued parking fines.
A total of 4,592 tickets were issued through 12 cameras which had not been authorised for use by the Vehicle Certification Agency between March 2009 to February 2013.
Officials said last year they would write off any unpaid fines - amounting to a total £216,133 - but would not refund fines already paid. Now, however, now it has written to those affected explaining they can indeed claim a refund.
Already 2,643 refunds have been claimed and 1,192 processed at a cost of £106,843.
The tickets were found to be issued unlawfully after an independent audit.
The National Motoring Action Group campaigned for the repayments and said councils should be more cautious in trying to retain penalty charges acquired unlawfully when they have had to stop enforcement. A council spokesman told the BBC steps had been taken to ensure the certification is maintained from now on.
RAC spokesman Simon Williams said: "This is good news for the these drivers and for others in the Newham area who now won't be issued illegal parking fines. We would like to know whether this is an isolated case or whether there are more councils using unauthorised cameras."
Copyright Press Association 2014