Can a pork roll (or barm for you other lot) be considered a sandwich?

I ask because I was in a place last night that had the 'Soho Special', steady, and it was noted on the menu that it was voted London's best sandwich by Capital Radio (quite an honour I'm sure you'll agree, I might start another thread on that annoying Capital Radio ad featuring Rihanna, Black Eyed Peas and other idiots at another time).

Anyway the roll fell apart because the filling was too hot and moist but I was thinking that surely it's a roll and not a sandwich. There is a difference. I wouldn't call a hamburger a sandwich. Does a sandwich have to involve sliced bread, I think it does.

Thanks for reading.