Sir Nigel Sheinwald, ambassador in Washington since last year, delivered his unvarnished assessment of the White House front runner in a seven-page letter to the Prime Minister, obtained by The Daily Telegraph, just before the Democratic nominee's visit to Downing Street just over two months ago.
The candid letter, marked as containing "sensitive judgements" and requesting officials to "protect the contents carefully" gives a remarkable insight into how the Foreign Office views the political phenomenon who stunned Mr Brown's inner circle by defeating their favourite, Hillary Clinton, in the Democratic primaries.
Although the picture Sir Nigel paints is a highly complimentary one - Mr Obama's speeches are "elegant" and "mesmerising", he is "highly intelligent" and has "star quality" - he also judges that his "policies are still evolving" and that if elected he will "have less of a track record than any recent president".
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