I think the unwritten rule is that if you see more than three hot Tinseltown “it girls” photographed carrying the same purse, it automatically becomes the next “it bag.” So when the likes of Kate Bosworth, Lindsay Lohan, Kate Moss and Sienna Miller were all seen out and about toting a version of the Mulberry’s Mabel satchel since it was debuted last year, lightbulbs went off in fashionistas’ heads everywhere, and the hunt for a Mabel of their own ...