LONDON, Jan 20 (Reuters) - British police fined Prime Minister Rishi Sunak on Friday for travelling in the back seat of a car without wearing his seat belt while filming a social media clip, a potentially embarrassing blow as he tries to revive his party's fortunes. Sunak, who apologised on Thursday for a "brief error of judgement", filmed a video in the back seat of his car while travelling in the north of England, without wearing a seat belt. "The prime minister fully accepts this was a mistake and has apologised. It is the second penalty Sunak has received from police after last year they found he broke COVID-19 lockdown rules, along with then-prime minister Boris Johnson. Sunak becomes the second prime minister after Johnson to have been fined in such a manner.

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