As her husband, Professor William Ayrton, once said to her cousin, Dr Philip Hartog, “you and I are able people, but Hertha is a genius.”

She was born in 1854 as Sarah Marks, the third child of a Polish Jewish watchmaker. Her father died in 1861, leaving Sarah’s mother with seven children and an eighth expected. Sarah certainly took on some of the responsibility for caring for the younger children, one that she never relinquished in the case of her younger sister, Lavinia, but her mother, Alice Marks, was a very strong woman.