SPARE a thought for society hairdresser Kim Robinson. For if we are to go by what he's been saying to anyone who would listen, then he spent much of the weekend sweating it out in a sauna desperately trying to shed some excess kilos. This sudden get-slim-quick fad has nothing to do with Robinson suffering withdrawal symptoms every time he looks at his wardrobe. On the contrary, it is to do with an appointment he has today to attend on the locks of wafer-thin British catwalk queen Kate Moss, who manages to make anorexics look positively obese. Moss, who will be modelling at the Gucci show in the Grand Hyatt ballroom tonight, is said to exist on a diet of black coffee and cigarettes; unlike Robinson, who gets by on caviar and champagne. They should have a lot to talk about.