When her father Bill ran for the presidency in 1992, Chelsea Clinton was a gawky 12-year-old with braces and a mop of crinkly hair, ill at ease in front of the cameras. Some 15 years later, her mother Hillary has assigned her daughter a crucial role in the family's latest White House campaign as the former First Lady hopes to firm up support among women voters with a "mum strategy". Miss Clinton, 26, who now works for a Wall Street hedge fund, has not appeared alongside her mother since the New York senator launched her presidential bid last weekend, but...