As a young policeman, he wrote a book of funny stories about working the night shift, but publishers weren't interested. Discouraged, he stopped writing. Years later, he was in a pub. Knowing that Walker had done some writing, the landlord asked him to give some advice to another customer who had written some stories. Walker asked the writer, "What kind of stories are they?" The reply was "It's a collection of funny stories about being a vet." The hopeful writer was Alf Wight. "There's no market for Yorkshire humor", Walker told him. Wight ignored that advice; using the pseudonym James Herriot, he wrote "All Creatures Great and Small". Encouraged by Wight's success, Walker wrote a new novel about the trials and tribulations of a rural Yorkshire policeman; it was the first of about 35 books in his "Constable" series.