The school cadet corps, a national program now known as the Combined Cadet Force, was formed towards the end of 1917 and 120 cadets were recruited within a month. The governors provided £25 towards their initial expenses, and volunteers contributed haversacks, water bottles, dummy rifles and trips to summer camp. Training initially took place on the Tonbridge School rifle range. By 1952, the number of volunteer cadets had fallen to 90. During the 1970s, numbers averaged about 150 cadets. The school's Combined Cadet Force currently comprises both an Army and a Royal Air Force Section with a total establishment strength of 120 cadets, who meet on Friday afternoons following a full school day. Membership remains voluntary, and boys can join from Year Nine (aged 13–14).