Unsurprisingly, the politically motivated 50% top tax rate introduced by Darling in last week's budget has proven to be an own goal.The Treasury admitted that billions of pounds of revenue would be lost, as high earners take the high road and leave the UK.Mike Williams, the director of personal tax at the Treasury, told the Treasury Select Committee that only 31% of the possible total income from the tax increase will be received by the Treasury. Last week the Chancellor said that the rate change would raise £1.1BN. However, figures now show that...