For his James Bond Dossier (1965), Kingsley Amis went through the 12 Ian Fleming books in which the character M appears and found that they give “a depressingly unvaried picture of what he’s like to be with, or anyway work for.” M’s demeanor or voice is described as:

• abrupt, angry (3 times)
• brutal, cold (7 times)
• curt, dry (5 times)
• frosty (2 times)
• gruff (7 times)
• hard (3 times)
• impatient (7 times)
• irritable (2 times)
• moody, severe, sharp (2 times)
• short (4 times)
• sour (2 times)

Amis says this “divides out as an irascibility index of just under 4.6 per book.”

The character seems to be a composite of several people whom Fleming had known, but he appears to be modeled most closely on Rear Admiral John Godfrey (above), Fleming’s superior at the Naval Intelligence Division during World War II. After Fleming’s death, Godfrey complained, “He turned me into that unsavoury character, M.”