Well, unless either of them struck up a conversation with me first (and even then my tongue, along with the rest of me, would probably be paralyzed), I wouldn't say or do anything save steal a couple of discrete glances and feel warm and tingly all over.
I have this thing about approaching famous people when they're in their own personal space. Ed and I were in the West End about 10 years ago, and I remember I had recently seen "Mrs. Brown" for the first time and was completely in awe of Judi Dench. We were waiting for the double-decker tour bus to make its rounds back to our stop and noticed a group of people coming out of a theater about 10 yards from where we were standing. Suddenly the little group was mobbed by people with pens and books, and I said, "I wonder who it is?" As the crowd dissipated, I noticed a couple of theater actors I recognized - one, even, who was in the play we had just seen the night before. As the group of them separated, out emerged from the center none other than Judi Dench. I whispered to Ed, "Oh, my God. It's Judi Dench. The one we liked so much in that "Mrs. Brown" movie we watched a couple weeks ago, remember?" She was walking in our direction, but not looking at us - just straight ahead. I was trying very hard not to stare and to look nonchalant. I remember she had this umbrella she was carrying like a cane - it was almost as tall as she was. He whispered, "Well, go get her autograph." I said, "No way. If I'd known it was her when they were mobbing her, maybe, but not now that she's in her own space." She waved her umbrella for a taxi, and one immediately appeared and whisked her away. I've never regretted not bothering her.
