Richard Lacey, 70, pleaded guilty to a single charge of drink-driving in Powys last month after appearing at Llandrindod Wells Magistrates’ Court this week.

Lacey had to use the device he helped create after police were called to the scene of a road traffic collision on the A479 near Talgarth on 23 November.

He was banned from driving for 13 months, fined £600 and told to pay a £240 surcharge and £85 costs.

Lacey had mounted a roundabout in his Peugeot 208 GT Puretech, damaging a wheel and leaving the vehicle immobile.

The defendant told the court on Tuesday that he had drunk a couple of glasses of wine and a couple of pints with his lunch before the accident.

Prosecutor Shane Maddocks said Lacey, of Wallstytch Lane, Kington, was described as “wobbly” when police arrived on the scene after receiving a call from a member of the public.

“The defendant said he had drunk a couple of pints and a bottle of wine. He failed the roadside breath test and was arrested.”

Mr Maddocks said Lacey had no previous convictions.The proportion of alcohol in Lacey’s breath was recorded as 41 micrograms, exceeding the prescribed limit of 35 micrograms.Representing himself at the hearing, Lacey said: “I’ve really got nothing to say. I misjudged how much I’d drunk.

“I had a couple of glasses of wine with lunch and a few pints of beer,” he said.

“I’m retired. I designed breathalysers and used to work with the police.”

Lacey can reduce his ban by 13 weeks if he completes a drink-drive awareness course.