His public career was not over, as he was made Chairman of the Cambrian Housing Society in 1968. In the same year, he was appointed to the Council of the National Museum of Wales, on which he served for 26 years. In 1972 he was given a spot on the United Kingdom delegation to the European Community's Economic and Social Committee, on which he served until 1978. Under the Thatcher government, Rees was a member of the Welsh Development Agency from 1980 to 1986.