As Bond fans know, Fleming had a life and personality that mirrored his famous creation. He came from a posh Scottish banking family, and was a world traveler from a very early age. During World War 2, he was recruited from the Black Watch into Royal Navy Intelligence where he was the brainpower behind plans like Operation Goldeneye. His military background gave him a wealth of ideas for his Bond novels, and he eventually retired to Jamaica where he'd pen Casino Royale. By his own admission he always drank too much, smoke too much, and loved too many women -- all of which contributed to an early death at only 56 years old.
McAvoy has the right polish to be Fleming. It's a role better suited to him than his Wanted assassin, and his youth certainly works for Fleming's most exciting years. But considering Fleming was 44 years old when he began drafting his first Bond novel, I think they should have looked to an older Scotsman for the role. Kevin McKidd would have been better -- he looks more like Fleming, and he's mature enough for the Jamaica years. What do you think of McAvoy as the father of your favorite spy?
*ETA: Yes, I know Sean Connery was Scottish. I was speaking of the recasting which lead to Daniel Craig.