The Prisoner Of Azkaban brought with it a major shift in the series. With director Alfonso Cuarón replacing Christopher Columbus and the tone of the movies getting decidedly darker, it stands as the bridge between the original child adventures and the epic action that followed. Columbus was quite happy to leave the series, having barely come up for air during the production of the last two films, but before he did he had some involvement in Prisoner's pre-production. One piece of his input was suggesting casting Robson Green as Harry's godfather Sirius Black. Bringing in an actor whose work is exclusively in British television probably wouldn't have been the best choice for the ever growing series, which the rest of the film-makers obviously agreed with. Gary Oldman was eventually offered the part, although he only took it because he needed to money. Good, accidental choice Gary.
