Succeeded Bernard Lee as M in the James Bond films. However, it is not known if he is meant to be the same character, Admiral Sir Miles Messervy, or a different character promoted to be director of MI6. Complicating matters is the fact that Brown played a different character in The Spy Who Loved Me (1977). In The World Is Not Enough (1999), Brown's picture also does not appear in the office of the next M, Judi Dench, but Lee's does. However, later in No Time to Die (2021) a picture of Brown's M could be seen in a hall.

He was born and died in Swanage, Dorset, where his father had been coxswain of the town's lifeboat. In 1992, a lifeboat was named "Robert Charles Brown" after his father.

He went from playing Roger Moore's servant on Ivanhoe (1958) to becoming his superior in the Bond movies, starting with Octopussy (1983).

He appeared in three films with Bernard Lee, his predecessor as M: The Third Man (1949), Sink the Bismarck! (1960) and The Spy Who Loved Me (1977). Coincidentally, Geoffrey Keen appeared in all three films.

Studied acting in New York City at both the New School for Social Research's Dramatic Workshop and the American Theater Wing.