Yarrow spent most of her childhood in the woods, pretending to be characters from books. She especially liked the ones where children had to survive on their own. In 2009, she went to Oxford to study English and French Literature, and discovered that the Botanic Garden was the perfect place to revise for exams. After university, she became an English teacher where she especially enjoyed taking children outside to write stories. Since then, Yarrow has found herself in jobs that usually involve getting muddy, like working with rescue horses, and learning how to use chainsaws and tractors at the RSPB. She now lives on a narrowboat and travels around the canals of England looking for more opportunities to get muddy (and somewhere to keep her own sheep).