Columbia subject headings:
Churchill, Winston, 1874-1965.
Intelligence service--Great Britain--History--20th century.
Secret service--Great Britain--History--20th century.
Harvard subject headings:
Princeton subject headings:
Churchill, Winston, 1874-1965.
Espionage, British.
Great Britain--Foreign relations--20th century.
Great Britain. MI6
Intelligence service--Great Britain--History--20th century.
World War, 1939-1945--Secret service--Great Britain.