When I worked in Theatreland on the Tube (now shoved out to Zone 2 following re-organisation, unfortunately) I used to see the odd familiar face. Edwina Currie, Joanna Lumley, Paul McGann, Cheryl Baker...all utterly lovely. I am in professional mode and try not to treat them any differently from other commuters. There is the initial look of recognition, of course, but after that, just speak to them normally!
My husband is a postman in a vairy nice area and has had well known actors, comedians, pop stars and telly presenters as customers. His favourite customer is very chatty and will hold up the delivery to connect with my husband talking about TV and Movies they both like, and this actor gave DH £50 as a Christmas tip.
Another Actor was is Stella, and again, very nice person, very down to earth. My husband could tell you stories about the boyfriends that come and go from her house
. But luckily for them, DH is discreet, as am I
!