Perhaps us 40 something's could take a leaf out of Marie Helvin (the 70's supermodels) book, as she gives us an insight into how she looks so great at 56, in an interview with The Times.She says that her formula includes: slim silhouettes; 4in heels (but not higher); pencil skirts that graze the knee (???it???s not that I don???t like my legs, but I would never wear short any more, except on the b