In the 1960's, how did the Brits refer to teachers, principles, and disciplinarians in private school?

By private, I mean high tuition paid by wealthy people, to a boarding school where uniforms are worn and people were very high-society. Were they all Master So-and-so? I'm not sure if they said Professor Smith, Headmaster Smith, Master Smith... Is a Headmaster the same as a principle? Is the disciplinarian called a prefect? And if so, is he Master Smith, or Prefect Smith? Need help, as I'm writing a short story where the kid goes to school in England, and I don't want it to sound wrong and be obvious an American wrote it!!!