In the short story The Case of the Missing Lady, Dr Brady is a doctor and an acquaintance of Tommy and Tuppence. When Tommy and Tuppence encountered Dr Horriston in the village of Maldon Sussex, Tommy called Brady for background information on the doctor. Brady had heard of Horriston. He told Tommy that Horriston had once been a bona fide doctor but had been struck off the register for some reason. Brady considered him "a most unscrupulous quack".
Dr Brady is not fetured in LWT's 1984 adaptation of the story. There, Tuppence had already heard of Horriston herself because one of her friends had been his patient.