sentences:  Between 1949 and 1953, he was principal private secretary to the three successive Chancellors of the Exchequer Sir Stafford Cripps, Hugh Gaitskell and then R. A. Butler.Armstrong was Under-Secretary to the Overseas Finance Division of the Treasury from 1953 to 1957, and from 1957 to 1958 of the Home Finance Division.Between 1958 and 1962, he was Third Secretary and Treasury Officer of Accounts.