Of all the claims in support of John McCain's bid for the White House, perhaps none is quite as grand as this. As he arrived in London today, the publishers of his new book insisted the Republican senator's family was descended from the Scottish king, Robert the Bruce. For a veteran war hero staking his presidential campaign on military credentials, an ancestral link to a warrior who overcame the English to reclaim Scottish independence in 1314 has obvious appeal. But according to experts, the story may be no more than that. Asked by the Guardian to investigate McCain's past, genealogists...