Born in 1883 in Chipstead, Marguerite Harcourt Burrage was the daughter of journalist and prolific boys' author Edwin Harcourt Burrage, and his wife Alice Louisa Reynolds. The only surviving daughter of the marriage, she had seven brothers, one of whom - Athol Harcourt Burrage - became an author of boys' stories like their father. Another brother, Douglas Burrage, became a circus performer, eventually publishing two books about his experiences. Her cousin, A.M. Burrage (not to be confused with her brother, who published as A.H. Burrage), was also an author.
Burrage, known as 'Rita' to her family, was educated at Gore House, Redhill, and at an Ursuline convent in Brussels. She married insurance agent William Bentley Coatts in 1907, moving with him briefly to Canada, before returning to England, where they separated, and eventually divorced. They had one son, born in 1909. Coatts settled in Greatstone, on the Kentish coast, after the separation, turning to writing to supplement her income, authoring approximately thirty girls' school stories, and children's thrillers.