Hartlepool mum Michelle Plant was twice caught speeding on Easington Road, Hartlepool, doing 36mph and 37mph back in May and June 2005.

She appealed against her conviction at Teesside Crown Court where Recorder Martin Bethel ruled in her favour.

He decided that the Section 172 document used by Cleveland Police was not legal because it did not mention the Chief Officer of Police anywhere in the document and it did not warn people of a potential criminal conviction if they failed to fill it in.

Michelle, from the town's Woodstock Way, told the Mail: "I'm actually relieved that it's been sorted out. I feel as if I've been brought into something that I wouldn't have got into in the first place if I had been aware of the speed limit on Easington Road."

She added: "It's the law breaking the law, but they're expecting all these people to put this money up."

Michelle is now the third person in the Cleveland area to have their fines overturned on the grounds that the section 172 notice is not a legal document.

Her legal team say more convicted drivers in the Cleveland area could follow her lead.

Michelle, a community artist in the town, initially appealed against her conviction on the basis of poor signage, but after taking on a specialist solicitor from Leeds firm, Andrew Thompson and Co solicitors, they soon realised that there were other grounds for her appeal.

Andrew Thompson said: "There have been three appeals on this very point and all three have won.

"These are not one offs or flukes. This is a system failure by the police and they have been exposed and caught."

Michelle, who was reimbursed £120 and had the six points removed from her licence, is now urging other drivers who have been convicted on the basis of the defective notice for speeding or failing to provide driver details to seek legal advice.

"By right, if I have got off, they should get off, whoever they are - because it was illegal in the first place," she said.

Michelle, 45, who is married to Stephen Plant, initially pleaded not guilty before a circuit judge at Hartlepool Magistrates Court, but he ruled against her.

"I said I would like to take it further," said Michelle.

"I was prepared to take it further on the basis of signs, but I ended up getting off on the technicality that the papers hadn't been signed correctly."

The witness expert in the case, Richard Bentley, of RMB Consulting, said: "Looking at the financial accounts of the Cleveland Safety Camera Partnership, it could be anything up to 18,000 motorists who have been through the court system and could now appeal."

A spokeswoman for Cleveland Police said: "Cleveland Police has amended its Section 172 forms since comments made at Crown Court by Judge Bowers in July, last year.

"Mrs Plant took forward her particular case (which pre-dated July 2006) as was her right to do so and the court decided that despite a speeding offence having taken place, it would be inappropriate for her to be convicted.

"Anyone dealt with since July 2006 will not be in a position to use this legal technicality to avoid conviction and each case will be dealt with on its individual merit."

Who may win

Years of controversy