Columbia subject headings:
Great Britain. MI5--History.
Intelligence service--Great Britain--History.
Harvard subject headings:
Great Britain. MI5--History--1945-
Great Britain. MI5--History.
Intelligence service--Great Britain--History--1945-
Secret service--Great Britain--History--1945-
Secret service--Great Britain--History.
Princeton subject headings:
Great Britain. MI5--History.
Intelligence service--Great Britain--History.