Just the other night.
My brother was arrested on suspicion of threatening some kid with a knife... obviously it didn't happen, and they took a bread knife that was in the kitchen sink as evidence
I was the only other person home at the time so it was a bit odd. But I did get to make S&M jokes with the police officer, who btw was a total babe, and we chatted about GTA online and stuff... he was either very casual or knew my brother was innocent
As for me personally, only once - I was assaulted on the high street one time by some total randomer, but it was caught on CCTV. He got a warning
I've given witness statements 2 or 3 times too.