 On his return to Britain , Horrocks took up the modern pentathlon . He competed successfully in army tournaments , and was picked for the British Olympic team for the 1924 Paris Olympics , where he finished 19th out of 38 . Horrocks spent the remainder of the inter @-@ war years in postings that included adjutant for the 9th Battalion , Middlesex Regiment of the Territorial Army ( 1926 – 1930 ) ; student at the Staff College , Camberley ( 1931 – 32 ) ; Staff Captain at the War Office ( 1934 – 36 ) ; brigade major with the 5th Infantry Brigade ( 1936 – 38 ) ; and instructor at the Staff College . The Territorial Army posting , which Horrocks considered to be among his happiest periods , provided experience in dealing with citizen soldiers , which would prove highly valuable during the Second World War . He received a brevet majority in 1935 , and was promoted to substantive major in 1936 , and brevet lieutenant colonel in 1937 . 
