Havergal, together with her elder sister Frances, attended St Katherine's boarding school in Walmer after 1912, but after her parents divorced in 1914, she and her siblings moved with their mother to Bedford, where they lived at number 13 Sidney Road, and the children attended Bedford High School.

Havergal began working in horticulture after leaving school in 1916, taking on local gardening jobs under the auspices of the Women's War Agricultural Committee.

She subsequently attended the Thatcham Fruit and Flower Farm near Newbury, wherem she graduated in 1920, obtaining the Royal Horticultural Society's certificate with honours.

Havergal's first professional challenge was to design and create a garden at Cold Ash in Berkshire, where the high quality of her work brought her to the attention of Olive Willis, the headmistress of the nearby Downe House boarding school.

Whilst at Downe House, she met the school's housekeeper, Avice Sanders, with whom she would remain partnered for the rest of the latter's life.

A copy of this letter is held at the Roald Dahl Museum and Story Centre in Great Missenden, Buckinghamshire.

[2] Havergal's diploma was accepted by the Institute of Parks Administration as one equal to those issued by Kew and Edinburgh.

[2] For many years Havergal won gold medal for her exhibit of Royal Sovereign strawberries at Chelsea Flower Show.