Wow, we have a British expression which was originated by an obscure line in a song from a singer who's probably only listened to by a very small minority of middle-aged, middle-class British people? Hmmm. Let's just ignore the most popular theory, that it came from the youth of the early to mid-1990s, then!

Anyway, here's someone who seems to at least partially agree with me:
http://english2american.com/dictionary/cat_clothing.html

and another definition:

http://www.peevish.co.uk/slang/p.htm

and an interesting (and embarrassing) example of usage:

http://news.bbc.co.uk/1/hi/special_report/1999/02/99/e-cyclopedia/1076585.stm

and, finally, what Michael Quinion has to say:

http://www.worldwidewords.org/topicalwords/tw-pan4.htm