Gill was the only daughter of George Clarence Yeaxlee and Laura Florence Yeaxlee (nee Foreman). She has an older brother, David. The Yeaxlee family lived in Harpenden for many years and ran a Grocer's shop on Southdown Road for several years. It became a Londis shop under George and Laura's ownership. George and Laura had lived in Purley in South London before then moving to Harpenden when David was five and Gill was around three years old. George was a qualified electrician and also a very good carpenter. Laura had been Head Telephonist at an exchange in London. George was the son of Clarence Hamilton Yeaxlee, who was the younger brother of celebrated academic and author, Basil Alfred Yeaxlee. Basil was Dean at Westhill College in Birmingham from 1930 and an adviser to Sir Winston Churchill on education and religion.