When does All Creatures Great and Small return?

All Creatures Great and Small is a British television series based on Alf Wight's books. The title aired over seven series, totalling 90 episodes, from 1978 to 1990. It stars Christopher Timothy as James Herriot, Siegfried Farnon, Helen Herriot and Tristan Farnon. The supporting cast, both recurring and one-off, numbers over 600, most of whom appear as farmers or clients of the surgery.