^ I never thought of that, but yeah, Knotts is really similar to Thorpe. It's hard to say though really, because like Jordan said, the marketing of Merlin and Six Flags is kind of similar, though as far as the way the parks look and stuff, it'd be really hard to say. Thorpe would certainly be more like Cedar Fair I think, but Alton can't really be compared to anything over here. I guess you could stretch it and say Disney because of the atmosphere of being somewhere else, but then what about Chessington?
I know this post wasn't very helpful, I just don't see how you're gonna find something similar enough to Merlin to do a good paper on it :S The Merlin parks are all so different from eachother.