I'm really bad at recognising people, and when I see someone well-known, they look familiar and but I'm never sure where I know them from.
In 2019, DP and I were sitting in a pub garden with the dog, and this big tall man came over with his two little girls and asked if it would be all right if they said hello to the dog. It was, and they did, and we had a bit of a chat about her breed, age etc. They were a really pleasant family, and I was certain I'd met the man before.
As we got in the car, I told DP that I was positive I knew the bloke, but couldn't place him. He gave me a pitying look and said "That was Mark Williams" but I was adamant I didn't know a Mark Williams. DP then reeled off loads of the tv and films Mark Williams had done. After that, I saw him* a few times in town and he always said hello.
I also once said hello to David Dimbleby in Waitrose because I thought I knew him, and Boris Becker, who lived in the same town as me for a little while.
I don't know if politicians count, but I've met loads, mostly Labour (Tony Benn, Michael Foot, Ken Livingstone, John McDonnell, Jeremy Corbyn, Diane Abbot, Margaret Hodge, Glenys Kinnock are probably the best known) but also 2 former Speakers (John Bercow and Bernard Weatherill) and former minister Amber Rudd. My area seems to be a bit of sunset home for old politicians, and at one time we had James Callaghan, Denis Healy and Kenneth Baker living nearby and I've met them all at various times (Healy and Callaghan were grumpy, Baker was utterly charming, which was a bit of a disappointment for an old lefty like me.)
*Mark Williams, not my late DP!