A prolific English author who sold over 100 million copies of her books, she is best known for the Kate Hannigan series, the Mary Ann stories, the Bill Bailey trilogy, and numerous other novels for adults and children. She sometimes wrote under the pen names of Katie McMullen and Catherine Marchant.
She dropped out of school when she was just thirteen years old and worked as a domestic servant. She published her first literary work, Kate Hannigan, in 1950.
She suffered a psychological breakdown in her mid-thirties as a result of experiencing four miscarriages. She began writing in an attempt to overcome her depression.
She was born to an unwed mother and was raised by her grandparents; she grew up thinking that her biological mother, Kate Fawcett, was actually her sister. She married Tom Cookson, an elementary school teacher, when she was thirty-four years old.
She and W. H. Auden are both famous English authors.