My area is similarly special: I'm doing television studies, but my research is on generic hybridity and formal and textual changes in post-1992 US and UK sitcoms. Worldwide, there aren't many people working on sitcoms, and I think I might be the only one working on this era in this way.
Needless to say, it was incredibly important that I get supervisors who could handle my work. It really didn't matter what the university itself was like. As it's worked out, there are some problems with Roehampton, but I work with people who have expertise in a lot of the areas that combine in my thesis.
I could go elsewhere for various reasons, but I'd be screwed.