Danny Boyle during the preparations for the 2012 Opening Ceremony, very nice, kind and extremely patient. To be fair, the whole creative team were very nice, no one shouted or lost their patience, which probably was a hard thing with several thousand amateur volunteers.
Davina McCall and Paloma Faith at an event in Birmingham, Davina was lovely, down to earth and very funny. Paloma Faith had quite an attitude and did not want to be talked to by anyone but her team.
William, Kate and Harry two years ago when I was volunteering at the London Marathon, lovely and polite, seemed genuinely happy to be there.
Richard E. Grant was in front of me in the queue in my bank (that was before the Oscar nomination), he seemed very nice and "normal", didn't accept the special treatment offered to him.
At an immersive show type of thing I was volunteering at:
Georgia May Jagger: Very humble and genuinely surprised, looked very young
Dustin Lance Black: Very informed and intelligent
Suki Waterhouse: Very DYKWIA, had a go at me for preventing her from falling on her pretty face
Boy George: Almost unrecognisable without his make up
"Just" seen:
Sophie of Wessex, walking up the hill with her son in my corner of SW London, I had a is it her, is it not moment, but the security detail gave it away
Bill Nighy while my sister was visiting me and about five minutes after I had said I never recognise anyone.
Alex Kingston was filming an ITV drama outside my office building a few years ago
Domnhall Gleeson filming a few weeks ago
Helena Bonham Carter in Belsize Park on Saturday, she looks quite young and smiled at me. Took me a split second to realise who that was.
Allegedly there are a quite a few "celebs" shopping at my local supermarket, but I usually don't pay any attention to anything else than getting in and out of the shop as quickly as possible. I also suspect, they would not go shopping during the after work rush hour.
I have to add, I would never ask anyone for an autograph unless it was at a premiere, at a theatre stage door or otherwise clearly "at work". Famous they might be, but I believe they also have a right to privacy.