Hate to tell you this but, Darrowby is a fictitious place. He used Thirsk as the setting for the village in the book.
http://www.thirsk.org.uk/
Very true though about Herriots writing style. If you ever get chance and can find them on dvd, All Creatures Great and Small the televised version (not the film, but the many episodes with Christopher Timothy as James Herriott)
Thirsk is about 60 miles away from us.