A high court judge delivered a scathing attack on the lack of discretion shown by London's congestion charging regime, in a ruling which could trigger a wider rethink over how traffic appeals are handled.

Mr Justice Stanley Burnton yesterday ruled in favour of a Liberal Democrat peer, Lady Walmsley, who has spent nearly two years contesting fines for driving her Fiat Puma into the centre of the capital.

Lady Walmsley said she had tried to pay the £5-a-day charge on two consecutive days in October 2003 but had made a mistake in inputting her number plate on Transport for London's website.

When she was sent penalty notices demanding £80 for two days' driving, Lady Walmsley realised her error and tried to tell TfL and London's Parking and Traffic Appeals Service, which arbitrates disputes.

She told the court that fighting the enforcement regime was like challenging "a blind and deaf Big Brother".

The appeals service said it lacked the discretion to overturn fines if TfL had followed the letter of the law.

But the judge rejected its argument, saying: "It is not a purpose of the scheme to penalise those who make a genuine error as to their vehicle's registration number.

"As has been seen, many people do make such errors and are relieved of penalty. It is and must always have been obvious to Transport for London that there were bound to be many people who would mis-state the registration numbers of their vehicles."

The ruling will be examined closely by authorities across Britain, which routinely argue they cannot bend rules on parking and traffic offences.

TfL has changed its procedures since Lady Walmsley received her fines and introduced a facility for representations which gives staff power to overturn penalty charges.