A number of years ago, a car side swipped my parked car in Newcastle just as I was approaching it.
I followed the car, and at the next lights, "politely" told the driver that he had hit my car. He just drove off through the red lights. I kept following him, and eventually he pulled up, locked his car and started to walk away.
I parked, and challenged him. To which, he said it was not his car. My assessment was that he had been drinking.

He refused to show me his licence, or identify himself. In turn, I said that I would not let him back in his car, as he was not fit to drive.
This distressed him, and he asked how he was going to get home. I suggested that he walk, but he said it was too far.
After a little more standoff, I got a brain wave. I offered to drive him home. And he accepted!!
I tried to head to the Police Station, but he was on to that. So I dropped him off at an address, and departed around the corner. Parked, and then watched which place he entered.
Hurried back to pick up the wife and kids by the side of the road (you guessed it, I was not popular). After dropping the family at friends (we ere only visiting Newcastle that day), went to the Police Station to report the incident. Got a good response, and they went and collected said driver.
Anyhow, the statutory time for a breath test after an accident had passed before they found him hiding in bushes in the back yard. They bought him in for questioning, and charged him.
As there was no test result, the prosecution case depended on the court accepting me as an expert witness in "inebriation".
Anyhow, on the day of the hearing, the accused told the magistrate that I was wrong, and he had not been drinking that night. The magistrate asked him was this claim was so different to the statement made to the police on the night he was arrested.
His logical answer to that was, "It wasn't fair that they took a statement from me that night, considering the condition I was in!!!".
I didn't even need to give evidence. He was remanded for a pre-sentence report as he had previosuly had 4 DUI's.