“The British constitution, Lord Bryce once said, ‘works by a body of understandings which no writer can formulate’. But these ‘understandings’, insofar as they relate to a hung Parliament, have now been formulated in a Cabinet Office manual produced under the aegis of the Cabinet Secretary, Sir Gus O’Donnell. I was involved in helping to draw it up.”
The Times, 29th April 2010
Source: www.timesonline.co.uk