From the LA Times:
Michael Gambon has played Hogwarts headmaster Albus Dumbledore for five years but he hasn’t been setting a good example for his students when it comes to finishing their homework: The beloved old wizard hasn’t cracked a single one of J.K. Rowling’s “Harry Potter” novels.
The choice not to read Rowlingâ€™s book series, he explains, is deliberate and he points out that costars Ralph Fiennes and Alan Rickman havenâ€™t taken up the books either.
â€œYouâ€™d get upset about all the scenes it’s missing from the book, wouldnâ€˜t you?â€ Gambon said via phone from New York, where he was promoting the opening this Wednesday of the sixth “Potter” film. â€œNo point in reading the books because youâ€™re playing with [screenwriter] Steve Klovesâ€™ words.â€
This might explain why his portrayal of Dumbledore has been abysmal. Dumbledore in the books had a quiet air of authority derived from respect of his peers and students. Gambon plays the part like a shrieking speed freak. RIP Richard Harris.