Horrocks was promoted to
lieutenant colonel on 19 May 1911, then in July was promoted
brevet colonel dated 20 May, in recognition of his services. In 1915, Horrocks was honoured by becoming an Honorary Surgeon to
King George V, commencing 6 November 1914, holding the appointment until 26 December 1917. Horrocks also developed the "Horrocks Box", following his research into contamination of water. This device used
sand filtration and
chlorine sterilisation plants to provide a portable means of decontaminating water supplies. It proved of particular use during the
First World War, when it kept the
Allied forces largely free of water-borne disease. In addition to this he also developed means of removing poisons from water and assisted in the design of the first
gas mask. For his services in the war, Horrocks was honoured with appointments to a number of
orders. On 24 January 1917 he was appointed a
Companion of the Bath. On 3 June 1918 (in the
King's Birthday Honours) Horrocks was appointed a
Knight Commander of the Order of Saint Michael and Saint George. He became the first Director of Hygiene at the
War Office on 1 June 1919 in recognition of his expertise in military hygiene, this last period of active duty came to an end on 1 November 1919, and he relinquished his temporary rank of
Brigadier-General. Horrocks died on 26 January 1941 at the age of eighty-one, at
Hersham in
Surrey. His
funeral took place at St. Peter's Church, Hersham on 31 January with his son and daughter, among others, present. ==Notes==