His whimsical tales often revolve around boys' preparatory schools in Great Britain and often involve sports like cricket, pranks, and mysteries, as well as a beloved pet bulldog, Uggles.

Books authored by Mills on the shelves of the British Library[1] include Meredith and Co.: The Story of a Modern Preparatory School [1933], King Willow [1938], Minor and Major [1939], and St. Thomas of Canterbury [1939].

Mills had fought in World War I from 1916 to 1919, beginning as a Private in a Rifle Brigade, transferring to the Royal Army Service Corps, and being discharged as a Lance Corporal.

At the outset of the World War II, Mills returned to military service on 11 October 1940 and was assigned the rank of Lieutenant as a paymaster in the Royal Army Pay Corps.

He was the grandson of Arthur Mills (MP) representing Taunton and Exeter, and Sir George Dalhousie Ramsay, CB, who spent thirty years as the Director of Army Clothing at the Royal Army Clothing Depot in Pimlico (1863–1893), and the second son of Revd Barton R. V. Mills, a cleric and scholar who was an authority on the works of St. Bernard of Clairvaux.