Rugby legend JPR Williams was fined £380 and banned from driving for 17 months after being caught putting coins in his mouth to try and trick a breath test, a court heard.
The former Welsh fullback, who played in the all-conquering Welsh sides of the 1970s, had spent the day watching a rugby match before he was stopped in his red Audi cabriolet.
The 61-year-old British Lions legend was taken to a police station after officers smelt alcohol on his breath, Cardiff Magistrates' Court heard.
Hannah Norton, prosecuting, said: "Mr Williams had to be instructed twice to remove items from his mouth, those being three one-penny coins.
"Your worships, there is a myth that copper from those coins can interfere with breathalyser machines at the police station."
A blood sample showed he had 142mg of alcohol in 100ml of blood. The legal limit is 80mg.
Williams was also ordered to pay a £15 victim surcharge and £85 costs. His ban will be reduced by four months if he carries out a driver rehabilitation course.
Speaking outside court, Williams' legal representation said his client regretted his actions.
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