Her political career took off after the war. She was elected for a term on
Barnes council where she served from 1945 – 1949. She was appointed a Dame Commander of the
Order of the British Empire (DBE) in September 1961. At the
1966 election, she lost her seat to Labour's
Alistair Macdonald, by a majority of only 810. Four years later, at the
1970 election, she regained the seat with a majority of 3363. Constituency boundary changes implemented in the
February 1974 general election encouraged Hornsby-Smith to allow
Roger Sims to stand for Chislehurst, and to compete instead for the new constituency of
Sidcup. However,
Edward Heath also selected to run for Sidcup so Hornsby-Smith stood in another new seat;
Aldridge-Brownhills. Hornsby-Smith was subsequently elevated to a life peerage on 13 May 1974 as
Baroness Hornsby-Smith, of
Chislehurst in
Greater London. ==Death and memorial==