Mr. Laser Beam wrote:

^ M is the same, and it's not HER first mission, so it doesn't have to be Q's either.
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M is played by the same actress, but she's not intended to be the same character from the Brosnan films. In those films she chastises Bond for being a relic of the Cold War, clearly indicating her character was never really part of the spy game during the cold war.
In Casino Royale M specifically mentions that she misses the Cold War.