Comedian Jimmy Carr was convicted of speeding.
The 37-year-old drove his Bentley GT at 50mph in a 40mph zone in Boxford, Suffolk, prosecutors said.
Carr, who was not present for the hearing at Bury St Edmunds Magistrates Court, was caught by a mobile speed camera on April 30 2008, prosecutor David Hutson said.
The offence took place the day after his sell-out performance at the Ipswich Regent.
Carr, of north London, was represented by celebrity lawyer Nick Freeman - known as Mr Loophole - who tried to argue that the speed limit was "defective" because the speed control order was ambiguous about road names.
The court heard the speed restriction on the A107, where Carr was caught, starts from 340 meters west of Boxford Lane. But Mr Freeman said that the road is in fact called School Hill.
Mr Freeman also argued that there had been an "abuse of process" at an earlier hearing.
However, District Judge Stuart Miller today dismissed the claims and awarded Carr three points on his licence.
He was told to pay a £300 fine and £15 victim surcharge.
DJ Miller also ordered Carr to pay £1,860 in prosecution costs and expert witness costs of £1,344.05.
Carr was found guilty after a trial which began in September.
Outside court Mr Freeman said Carr has 21 days to decide whether to appeal the outcome of the case.
After the hearing Crown Prosecution lawyer David Hutson said: "We take motoring offences very seriously and driving over the legal speed limit means the driver poses a danger to other road users.
"We are pleased with today's verdict and hope it acts as a deterrent to other speeding motorists."