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UK could face break-up - O'Donnell

Among the biggest challenges facing the United Kingdom in the years ahead is the potential break-up of the union itself, according to Britain's most senior civil servant.

Sir Gus O'Donnell is about to retire as cabinet secretary and his words have been taken as a signal that the biggest Westminster parties have not worked out a coherent response to the strategy being pursued by Scotland's First Minister, Alex Salmond of the SNP.

Lorna Gordon reports.