Humphrey was created by Annette Billingsley as a main character in her thirty-two book series of The Troubleseekers children's novels. He was chess player who had been taught the game by his grandfather.
Martha Jones described Humphrey as the group's "no-nonsense leader." In a world created by fictional books that Martha had read, Humphrey was temporarily brought to life by a Ch'otterai. (PROSE: The Mystery of the Haunted Cottage)