Sources:

Calvert, Colonel H. S., O.B.E., M.C. “With the 61 Light Regiment, R.A., in Korea.” Journal of the Royal Artillery, vol. LXXXI, no. 3, July 1954, pp. 191–200.
Obituary for Major (Qm) Harold Clapton, d. 29 Nov. 1975, Gunner, Mar. 1976.
"TwentyOne: Weekly Newspaper of the 21st Anti-Tank Regiment, Royal Artillery." Pinneberg, Schleswig-Holstein, Germany, 1945-1946.
United Kingdom. War Diaries - 61 Lt Regt RA. War Department, 1952-1953.
United Kingdom. War Diaries - 21 A/T Regt RA. War Department, 1944-1946.