The book dealt with Herriot's real-life experiences as a young veterinary surgeon in a Yorkshire farming community before the Second World War, many of them comical. Along with the series that followed, it became highly popular and in 1974 was made into a feature film of the same title, starring Simon Ward as James Herriot. Herriot's eccentric employer, Siegfried Farnon, was played by Anthony Hopkins.
In 1978, the BBC created a television series out of the books, again using the title, All Creatures Great and Small. The leading role was taken by an unknown actor, Christopher Timothy, and Siegfried Farnon was played by Robert Hardy. Siegfried's errant younger brother, Tristan Farnon, was played by Peter Davison, who became a household name as a result and went on take many other starring roles, notably as the fifth Doctor Who.
The series ran for several years, but broke off at the stage where the characters were drawn into the war. After a break of a few years, the series was revived, carrying on the story after the war with the same cast - except that James's wife, Helen, was now played by Lynda Bellingham.