I used to regard genres as being embedded in cliches, and I always felt funny about the need we have to label things. But I'm happy to think of 'Starred Up' as a prison drama, although we tried to smuggle in some elements of family drama in there.
When I started making films, all the theaters, the screen would slide open the widest possible point, and that would be widescreen. But now, theaters are geared up for around 16:9, so scope is now 'letterboxed.' In a way, if you want the big picture, you shoot 16:9.