The supporting cast, both recurring and one-offs, numbers over 600, most of whom appear as farmers or clients of the surgery. A total of ninety episodes was broadcast. The series had two runs: the original (1978 to 1980, based directly on Herriot's books) was for three series the second (1988 to 1990, filmed with original scripts but generally regarded as a continuation of the 1978 series) for four. This format greatly facilitated their adaptation for a television series. The Herriot novels were written in an episodic style, with each chapter generally containing a short story within the ongoing narrative of Herriot's life. It is part of a series of movies and television series based on Herriot's novels. In early 1977, the BBC tasked him with the creation of a television series from Herriot's first two novels, If Only They Could Talk (1970) and It Shouldn't Happen to a Vet (1972), using the title of the 1975 film adaptation. The series was produced throughout its run by Bill Sellars. Herriot's wife, Helen (based on Joan Wight), was initially played by Carol Drinkwater and in the latter series by Lynda Bellingham. Set in the Yorkshire Dales and beginning in the mid-1930s, it stars Christopher Timothy as Herriot, Robert Hardy as Siegfried Farnon (based on Donald Sinclair), the proprietor of the Skeldale House surgery, and Peter Davison as Siegfried's 'little brother', Tristan (based on Brian Sinclair). The title aired over seven series, totalling 90 episodes, from 1978 to 1990. All Creatures Great and Small is a British television series made by the BBC and based on the books of the British veterinary surgeon Alf Wight, who wrote under the pseudonym James Herriot.

All creatures great and small series