The Earl of Stockton crashed his Range Rover into two parked cars after he skipped lunch and had "some wine" at a local event before attempting to drive home.
Lord Stockton, Alexander Macmillan, 79, a hereditary peer and the grandson of former British prime minister Harold Macmillan, pleaded guilty to a drink driving charge at Wycombe Magistrates' Court on Tuesday and was banned from driving for 13 months.
He had been on his way home from a local event when he drove his black Range Rover into the parked cars on Old Mill Road in Denham, Bucks, on 31 July. He failed a roadside breath test after officers arrived at the scene.
The prosecutor told the court that Lord Stockton had skipped lunch that day but "drank some wine" at the local event before getting in his car.
He then managed to swerve his Range Rover into the parked cars while on his way home, causing minor damage to the vehicles, the court heard.
Police were called to the scene and Lord Stockton was taken into custody at Maidenhead police station, where he gave a reading of 42 micrograms of alcohol in 100 millilitres of breath. The legal limit is 35 micrograms.
Lord Stockton 'extremely sorry' for 'poor decision'
The former Conservative member of European Parliament told the court he was "extremely sorry" for what happened and regretted the "poor decision" he took to drive home that day.
The Denham resident, who also spent some time on the South Bucks District Council after he was voted in in 2011, pleaded guilty to the charge of drink driving levelled against him.
After the magistrates heard the evidence, Lord Stockton was fined £7,616 and told to pay £2,085 in costs. He was also given a 13-month disqualification that can be reduced by 13 weeks if he completes a driving awareness course.
Drink driving offences can carry sentences of up to six months in prison, an unlimited fine and at least a one year ban if a person drives, or attempts to drive while above the limit, or is found unfit through drink.
The large fine was imposed to reflect Lord Stockton's substantial income. He has appeared on the Sunday Times Rich List in the past, and in 2009 was estimated to be worth £160 million. He and his family sold their stake in the Macmillan publishing business for £130m in 1995. He had been president of the company.