He was also Honorary Colonel Commandant of the Chatham Division of the Royal Marines from 1941 to 1949. Foster died on 3 April 1966 aged 86. There is a memorial plaque to him in the East Surrey Regiment chapel, All Saints Church, Kingston upon Thames, Surrey. One of Foster's brothers, Lieutenant Archibald Courtenay Hayes Foster, was killed in action in British East Africa on 20 September 1914.