She is the daughter of Major Hubert Guy Broughton Knight (1917–1993) and Hester Loyd. Her sister, Celia Elizabeth Knight (1949–2020), was married to
Samuel Vestey, 3rd Baron Vestey. An
Oxford graduate, Knight worked as a biology and history teacher before becoming a trainer. She was a prominent figure in the equestrian sport of
eventing, finishing 12th at the
Badminton Horse Trials in 1973, and becoming the chairperson of the British Olympic Games Horse Trials Selection Committee from 1984 to 1988. This period included the selection of the Silver medal-winning team for the
Seoul Olympics. Knight began training
under rules in 1989 having previously trained over 100 winners on the amateur
point-to-point circuit from 1984 to 1989. Her training base is a farm in
West Lockinge, near Wantage in Oxfordshire. Knight married former champion National Hunt
jockey Terry Biddlecombe in 1995 and has no children. Biddlecombe died on 5 January 2014. Knight trained the
Jim and Valerie Lewis owned triple
Cheltenham Gold Cup winner
Best Mate (2002, 2003, 2004), Knight retired in 2012 with over 700 winners to her name. In November 2023, she announced that she would be returning to training.{{cite web|url=https://www.bbc.co.uk/sport/horse-racing/67331279 Knight is the author of five books:
Best Mate: Chasing Gold (2003);
Best Mate: Triple Gold (2004);
Not Enough Time - My Life with Terry Biddlecombe (2015);
The Jumping Game (2019);
Starting from Scratch: Inspired to be a Jump Jockey (2019). ==Major wins==