I really don't know. Nottingham was pretty shitty, but I'm pretty sure Derby is worse. I just can't remember if I've ever been there.
Also, the worst place I've ever visited was in London, it was horrible, run down, full of foreigners, and just generally a scary place, especially since we were meant to be staying in a hostel there for the weekend. Luckily, the guy charged us alot more than it said online, so we went to a nice hotel elsewhere.
The rest of London is nice enough though.