Therefore, Percival Macleod Yearsley did not write any books independently. John Creasey was a prolific author who wrote under a variety of pseudonyms. He is best known for his "Inspector West" series, but he wrote in several genres including thrillers, mysteries, Westerns, and science fiction.
If you are interested in learning more about John Creasey's work, you can find a list of his books under his own name and pseudonyms on websites like Goodreads or Wikipedia.