Cooksey was born in 1940, the elder daughter of Ian Aysgarth Bewley Cathie MD, of Barton House, Barton-on-the-Heath, Warwickshire, and his wife Dr Marian Josephine Cunning.

[4] Cooksey pursued her sport at the Polytechnic Fencing Club, London, which also produced Mary Glen-Haig, Sue Green, and Richard Cohen.

[6] As Janet Wardell-Yerburgh, she represented England and won double gold in the foil events at the 1966 British Empire and Commonwealth Games in Kingston, Jamaica.

[4] Poppy Cooksey graduated as a doctor of philosophy in Fine Arts from the University of St Andrews, and her thesis on the life and work of the Scottish painter Alexander Nasmyth was published in 1990.

[4] As a volunteer, she organized fund-raising events for the Royal National Lifeboat Institution and others for the building of a hospice for terminally sick children.

[12][4] In 1966, as Janet Bewley Cathie, she married the Olympic oarsman Hugh Wardell-Yerburgh,[2] and they had one daughter, Atlanta Jane, born in 1969.