Are surgeons properly addressed as "Mister" ??

Last night I finished reading a P. D. James mystery ("Cover Her Face," her debut novel and the initial appearance of Adam Dalgliesh).  Near the end I encountered this curious interchange:

"Not until eight o'clock tonight, Doctor."
Stung by his tone Stephen wanted, not for the first time, to point out that surgeons were addressed as "Mister."  He was saved from this pedantic pettiness by a realization of its futility...

The book was published in 1962; the setting of the story is somewhere in rural England at an unspecified time, probably in the 1940s-1960s.   I'm wondering whether the Mister/Doctor reference is an archaic use from an earlier time or whether it is still current, whether the application was used just for those performing surgery or extended to other medical physicians, and whether this convention extends beyond England/Great Britain/the British Isles/the British Commonwealth.