Sandys was responsible for establishing the
European Movement in Britain in
1947 and served as a member of the European Consultative Assembly in
1950 to
1951. He was elected to Parliament once again in
1950 for
Streatham and, when the Conservatives regained power, he was appointed as
Minister of Supply in
1951. For most of his time as Minister of Supply, his Private Secretary was
Jack Charles. As Minister of Housing from
1954, he introduced the
Clean Air Act and in
1955 introduced
green belts. He was appointed
Minister of Defence in
1957 and quickly produced the
1957 Defence White Paper that proposed a radical shift in the
Royal Air Force by ending the use of fighter aircraft in favour of
missile technology. Though later Ministers reversed the policy, the lost orders and cuts in research were responsible for several aircraft manufacturers going out of business. As Minister of Defence he saw the rationalization (ie merger) of much of the British military aircraft and engine industry - which led ultimately to a single airframe manufacturer
British Aerospace, and a single engine manufacturer
Rolls-Royce.
He divorced his first wife (
Diana Churchill) in
1960 and married Marie-Claire (
née Schmitt, previously married to Viscount Hudson) in
1962, the marriage lasting until his death. It has long been speculated that he may have been the 'headless man' whose identity was concealed during the scandalous divorce trial of
Margaret, Duchess of Argyll in
1963.
Sandys continued as a minister at the Commonwealth Relations Office, later combining it with the Colonies Office, until the Conservative government fell from power in
1964. In this role he was responsible for granting several colonies their independence.
He remained in the Shadow Cabinet until
1966 when he was sacked by
Edward Heath. He had strongly supported
Ian Smith in the dispute over
Rhodesia's Unilateral Declaration of Independence. He was not offered a post when the Conservatives won the 1970 general election, but instead served as Leader of the United Kingdom delegation to the
Council of Europe and
Western European Union until
1972 when he announced his retirement. The next year he was made a
Companion of Honour.
In
1974 he retired from Parliament and was awarded a life peerage. He followed the example of
George Brown and incorporated his first name in the title
Baron Duncan-Sandys, of the City of
Westminster. He was an active early member of the
Conservative Monday Club.
He has a daughter
Laura Sandys.