Denington became secretary to the National Association of Labour Teachers (1938–47), and taught in London junior schools until 1950.
[2] Denington became a member of London County Council's new and expanding towns committee, and served as chair of the design subcommittee.
During opposition (1967–1973), she became Labour's deputy leader on the Council, before serving as chair of the transport committee from 1973 to 1975, establishing free buses for pensioners.
[2] In 1974, she was promoted to Dame Commander of the Order of the British Empire,[6] and from 1975–76, she became chair of the Greater London Council.
She retired from the Greater London Council in 1977 and was created a life peer as Baroness Denington, of Stevenage in the County of Hertfordshire, on 10 July 1978.