Original title: The Duchess factor: How Catherine now shifts clothes faster than fashion's '$3billion woman' Michelle Obama ------------------------------- As if we needed any further proof that the new Duchess of Cambridge has serious fashion clout, it appears she has now surpassed Michelle Obama in selling power. Since her engagement to Prince William last year, everything Catherine wears now sells out in minutes, rivalling only the U.S. First Lady's impact on the industry. The Reiss Shola dress she wore to meet Mrs Obama last week was the strongest example to date. As soon as pictures of the Duchess appeared online, the...