In the novel The Secret Adversary, Sir William Beresford is the uncle of Tommy Beresford. Some time in his younger days, Sir William had wanted to adopt Tommy because he believed that Tommy's mother was no good. Tommy, however, refused to leave his mother. This resulted in the relations between Tommy and Sir William becoming strained.
Tommy and Sir William are, however, reconciled at the end of the story, through the efforts of Mr Carter. After learning from Carter about Tommy's work on behalf of the secret service, Sir William compliments Tommy and remarks that his mother must have brought him up well after all. He offers to let bygones be bygones and goes on to say that he intends to make Tommy his heir. He would henceforth give Tommy an allowance. In addition, Tommy is invited to move in and stay with Sir William at his house, Chalmers Park.