It was first published 1967. The doctors name was Sassall or Sewell......possibly.

Added, Doctor John Sassall. No, real name Doctor John Eskell. Only place name St Briavels.

See bjgp.blog.com/tag/johnsassal Note, Link doesn't seem to work.

RN Surgeon WWII. Manic depressive. Eskell's wife ran the surgery and died in 1981. Eskell/Sassal shot himself in 1982.