The revelation in today's Independent that John Prescott's biographer Colin Brown knew about his builimia but decided not to write about it in the book raises a few interesting questions about the art of political biography itself. If you're writing a biography of someone, is it not cheating the reader if you don't give the full story? If the reader has shelled out £18.99 shouldn't he or she expect to read about something which clearly had a huge effect on the former Deputy PM. Shouldn't the publisher have a right to expect total transparency?
Colin explains the omission by saying it would have "broken a confidence", a laudable reason in itself we'd probably all agree, but another understandable reason would be that breaking the confidence would in all probability have cost him one of his best sources for stories.
I have long thought it very difficult for lobby journalists to write proper authorised biographies as inevitably compromises have to made along the way. Yet it's also clear that they are the people best place to add the colour and anecdote that biographies written by historians or academics so often lack. I guess we should read them all with a health warning in our minds.