Sampson's early years held little clue that the man who entered figures in a ledger would someday spend most of his time pondering how to kill his victims for entertainment. After attending school in Warwickshire, he joined the army when World War I broke out. He became an officer in the infantry and served with distinction. After the war he became an accountant and eventually opened his own firm. He began writing after reading Malice Aforethought by Frances Illes, a work which made a powerful impression on him.
After the success of The Murder Of My Aunt, Hull published 14 more novels. He was well known for his wit, displayed in many of his novels. In 1940, he published a novel My Own Murderer in which the villain's name was Richard Henry Sampson.
He was a member of The Detection Club, a group of mystery writers who agreed to write novels that would give the reader a fair chance to guess "whodunit".