First elected to Parliament at the 1960 Petersfield by-election, Quennell had been chairman of the Horsham Divisional Conservative Association.
She stood down from parliament in the October 1974 general election, and continued to live at the family home near Rogate until her death.
Death
Quennell died in hospital in Chichester on 2 July 2006, having had recurring bouts of poor health since suffering a stroke a few years earlier. Her remains were cremated.[2]
Quennell bequeathed her Dangstein estate, near Rogate, to the National Trust.[3] In 2008, the Trust sold the estate to new owners who dismissed the staff and evicted tenants at the end of their agreements resulting in allegations that the Trust had not complied with Quennell's wishes.[4]