Of course, I am of the type that doesn't find Little Britain funny; catchphrases are only entaining to primary-school children; the rest of the program just pokes fun at stereotypes.
monty python created catch phrase humour. Have you never heard the live At...series where the whole crowed is reciting each sketch? And before Little Britain is was The Fast Show, then Harry Enfield. It becomes catch phrase because it's funny I suppose