The Pullein-Thompson sisters wrote their earliest books together.

Their very first book was It Began With Picotee, which they wrote together during WWII.

Before that they had had articles published in Riding Magazine, and they are included in the JBB edition of It Began With Picotee.

The sisters didn't give up writing together. They wrote a series of historical fiction, called Black Beauty's family. Each story was based on a relative or ancestor of Black Beauty, and set in a different time period.