A few years ago I read the biography of James Herriot written by his son. The series of books by JH (I will use the book/series names rather than their real names) are semi-autobiographical, with some situations being based on things experienced by colleagues, not by JH himself, and were in many cases exaggerated - poetic licence. One thing that came out at the start of the book was that Siegfried Farnon had recently lost his wife to TB just prior to JH joining the practice, a fact that was not mentioned at all in the books. After the first novel came out, Siegfried threatened to sue JH but eventually didn't.
At the end of the book is a section on how all the main people in the books died....
Callum Buchanan was the first to die, in a car accident in Canada where he had emigrated with his wife.
Tristan was (IIRC) the next to go, dying of natural causes.
James Herriot was next, again from natural causes.
One night, Siegfried went downstairs to where they kept the drugs, took an overdose of barbiturates and died a couple of days later.
Helen died from natural causes.
The practice is still there next to the James Herriot museum. The recent series uses items from the museum which were used in the practice when the series was set or were from the same time.
I've read the complete series several times and have both TV series on DVD as well as the two films that preceded them. Looking forward to the next series