Alfred Thompson Denning was born on January 23, 1899 in Whit church, Hampshire in the family of Charles Denning, a draper, and his wife Clara (Thompson). He was one of six children, the fourth of five sons. His sister Marjorie named him after Alfred the Great and he was baptized on April 23, 1899. Alfred was born two months earlier than expected and was weak and small. Because of this he was called "Tom Thumb". It is necessary to point out that this sobriquet became very popular: even as a Law Lord, Alfred Denning was sometimes surnamed as "Tom".
The range of Lord Denning's ancestors is impressive. Among them there is Sir Sydenham Poyntz, commanded the Parliamentary forces at the battle of Royton Heath in the Civil War, who afterwards became Governor of Antigua. The brother of Sydenham, Newdigate Poyntz fought for the King. His mother was a schoolmistress, a very strong lady with a backbone of steel. Her dream was to see her children successful. Maybe, it is family history that influenced the young Alfred greatly. But one thing is absolutely doubtful: this man prospered as one of the most influential British lawyers of the XX century.