O'Toole and Harris were best friends in real life, and their acting abilities are strikingly similar. He would have been perfect to replace Harris. But I wonder if they didn't want to take a chance on an older actor -- Gambon is 66 to O'Toole's (very hard living) 74. And both Baker and Briers are 73 as well. Maybe they didn't want to chance having to replace Dumbledore again?
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