Just for fun;
I found a video on Youtube with an interview with Rod Stewart that shows his mighty H0 scale layout that was also published in the ModelRailroader. According to this article (sorry, Dutch language only) he does a lot of modeling during tours. He carries a flightcase full of modeling stuff with him. In earlier days he smashed up hotelrooms, now he drinks a cup of tea and does some modeling.
Did make me wonder how many 'famous' that have modelrailroads are among us.
I remember reading once the actor John Mahoney had a layout.
I also remebered a very nice little article on Phil Collins who refused to get back to the studio's until he had finished his railway: Model trains keep Collins away from the studio
So I did some Googling and found a complete list on Wikipedia: List of transport modellers with some very big names, like Tom Hanks, Gene Hackman, Elton John, Ringo Starr, Bruce "the Boss" Springsteen, Frank Sinatra (wait I knew that) or Donald Sutherland... or Wallace and Gromit...
Did you know Neil Young owns a part of Lionel?
I would love to see some shots of their railways...
BTW: Also did found a list on Wikipedia on 'notable railfans' with some interesting names.