It was style queen Kate Moss who started this trend last year, and both Sienna Miller and Scarlett Johansson were quick to pick up on it.At recent fashion shows, the slim fit has been first up on the catwalk. Now it's over to you…But why is the slim fit back again and, more importantly, why should you be wearing it? Photo: Dior ready-to-wear fashion show, Autumn/Winter Collection 2006-2007