Marie-Hélène Arnaud in Chanel, 1959Photography courtesy of ChanelEach time fashion week draws to a close, we can often already envisage the brazen knock-offs that the shows might inspire: the Burberry Poncho, the Saint Laurent Glitter shoe and the Valentino studded heel are just a few examples that have been replicated across the high street in time for Christmas this year. Then there are the pieces that command longevity: the Chanel bouclé suit or Louboutin red sole remain a cons...