The author Jill Murphy began writing "The Worst Witch" at the age of 15, while still at school, and based many points of the stories on her own school experiences at Ursuline Convent in Wimbledon, England, with Singing becoming Chanting, Chemistry becoming Potions and so on. Recalling how she got the idea for the story, she said: "My two friends and I used to come home in our dark uniforms, looking very scruffy at the end of the day – my dark plaits sprouting tufts, with lost hair ribbons. My Mum used to say 'Look at you all. You look like the three witches!' and it gave me the idea for a witch's school – so that it was exactly like my school, but with a subtle touch of magic. All the characters are based on my school friends (and enemies) and teachers". Murphy concluded the first book at the age of 18, but failed to achieve a publishing deal, causing her to "put it in a drawer" and decide to "concentrate on other things instead". After working as a nanny and in a children's home, Murphy had a phone call from a small publisher interested in the book. "The Worst Witch" was finally published in 1974, when Murphy was 24.