During the Second World War, R. G. Pine-Coffin's older brother, E. C. Pine-Coffin, known as Claude to his family and friends, served in Malaya as a lieutenant colonel in the British Indian Army and was captured by the Japanese after the fall of Singapore in February 1942. Unlike many prisoners of war captured by the Japanese, Claude survived. R. G. himself had been commissioned into his local infantry regiment, the Devonshire Regiment, as a second lieutenant in 1928. He was promoted lieutenant in 1931, and captain in 1938. He was promoted major (war substantive) shortly after the beginning of the Second World War.