Apart from official events what is your strangest sighting of a celebrity?

I was contemplating this question earlier after overhearing a conversation whereby two people were talking about bumping into the comedian and actor Billy Connolly in the fruit and veg section of a supermarket and it got me thinking about my own strange encounters with people who were at least famous to me.

One of the strangest was getting on a train in Edinburgh and doing my usual of sitting down at a table and looking out the window until I became aware of someone sitting down at the same table. Usually I would just have a quick glance and carry on with my window viewing, but this time it was the lead singer of a Scottish band I loved in the 80s and 90s and there was this famous guy sitting with his expensive train station coffee and me resisting going…you….you are!!!

That being said what is your strangest encounter with someone who is famous? It does not have to be someone who is known globally, but someone who would be well known in and around your area? Have you ever been beside Tom Cruise when he is getting a big mac?