Sheffield motorist, Vikki Fielden, and her husband Iain, who defended his wife, said they have "no idea" how they will pay the costs after the appeal was dismissed yesterday.

The couple, who share a rented flat, narrowly escaped a much steeper bill of almost £25, 000 after the amount was reduced to take into account delays in disclosing evidence and the Fieldens' means.

It was a far cry from the three penalty points plus £200 costs and £100 fine Mrs Fielden was ordered to pay last year when she was convicted of speeding at 36mph in a 30mph zone on the A616 New Mill Road in Brockholes, just outside Huddersfield.

Yet the 49-year-old, who is unemployed, said she would go through it all again – even though the couple face borrowing money to pay the costs.

Fielden, of Shirecliffe Road, Sheffield, said: "It has taken a great deal of my husband's time and energy but it was worth doing even if it did not have the outcome that we would have expected.

"There is no way we can do it without borrowing. I am not sure we can borrow ."

Her physicist husband, who is a researcher/consultant for the Materials and Engineering Research Institute at Sheffield Hallam University and has won a national scientific measuring award, said he was shocked by the costs and would pay them "with difficulty."

Mr Fielden: "The whole point of coming here is not about the speeding – it is about following the instructions."

He said that the court had found the manufacturer's instructions for the speed camera had not been followed.

"The reason they have found my wife guilty is because it appears that the law does not require them to follow the manufacturer's instructions. As a scientist I believe it is an important point of principle that scientific instruments should be used properly by people who understand them," he said.

But road safety bosses took a different view.

Trevor Hall, managing director of Road Safety Support, and secretary to the Association of Chief Police Officers' (ACPO) Road Policing Enforcement Technology Committee and National Safety Camera co-ordinator, said: "The evidence presented against Vikki Fielden in this case was compelling from the outset. Mrs Fielden in her defence of this case has presented taxpayers with a large cost.

"Most motorists would have simply accepted the penalty and learned from their mistake.

"I hope the large cost awarded in this case will urge other motorists to think carefully before mounting spurious challenges often spurred on by anti-speed camera website material."

West Yorkshire Casualty Reduction Partnership spokesman, Philip Gwynne, said Mr Fielden appeared to be "defending his wife's honour" by "using the laws of physics."

He said: "However, the judge has ruled that in speeding cases it is the law of the land that matters – not the law of physics.

"Maybe it's time that we left physics in the classroom and allowed cameras to get on with their job which is to reduce injury and death on our roads and encourage people to drive within the speed limits," he continued.

Mr Fielden had argued that the speed camera was not being operated in accordance with the manufacturer's instructions and was, therefore, operating outside its type approval and that failure to follow the instruction manual had caused an erroneous reading

But at Bradford Crown Court, Recorder Jonathan Hill QC, who sat with two magistrates, said they were satisfied that the Gatso 24 AUS speed camera was operating accurately and that Fielden was exceeding the speed limit.

He said: "We are satisfied that this vehicle has followed a normal path for this stretch of road and that a normal path is something the Gatso is well capable of reading. The pictures clearly demonstrate that the vehicle was doing at least 36 mph."