He was elected as Member of Parliament (MP) for Camberwell North West in 1924 but was defeated in 1929. He returned to the House of Commons in a by-election in 1930 as member for Bromley and sat until his death, which occurred during the 1945 general election. Polling took place on 5 July 1945. Campbell died 12 days later, but nine days before the declaration of the result. He was declared posthumously elected on 26 July 1945, provoking a by-election in his Bromley constituency. That contest was won by Harold Macmillan. (Coincidentally, Leslie Pym, the member for Monmouth, died exactly the same day and was also posthumously elected.)
Frances Henriette Campbell (born Semarang, Java, Dutch East Indies, 30 November 1904), married on 16 December 1930 Rear AdmiralKeith McNeil Walter (later Campbell-Walter) (Hazaribagh, British India, 3 August 1904 – 24 April 1976), son of Alexander McNeill Walter, of Hazaribagh, India, ZamindariManager (Calcutta, British India, 12 May 1875 - Hazaribagh, British India, 12 February 1936), and wife Florence Ruth Gisella Downing (Purneah, Bengal, British India, 5 October 1879 – Egham, Surrey, 8 April 1976), whose daughter was:
Sir Charles Duncan Macnair Campbell, 2nd Baronet, of Airds (12 September 1906 – 16 January 1954; died unmarried and without issue, and the title became extinct with his death)
Craig, F. W. S. (1983) [1969]. British parliamentary election results 1918-1949 (3rd ed.). Chichester: Parliamentary Research Services. ISBN0-900178-06-X.
'Who's Who of British MPs: Volume IV, 1945-1979' by Michael Stenton and Stephen Lees (Harvester, Brighton, 1979) ISBN0-85527-335-6