Abigail Kamara, daughter of Alfred Kamara, is a nosy neighbour of Peter Grant's parents. By the time of James Gallagher's death, she was thirteen years old, which implies she was born in 1999. Abigail is mixed-race, her father being Sierra Leonean and her mother white. Once a week she goes to the Folly to report supernatural things she's seen. She has a brother.
During the summer of 2013 she may have worked on teenage missing person cases, and come to the attention of a senior Home Office civil servant. 
As of 2015, Abigail is being taught magic though still tends to rely on her wits and skills. Towards the end of a situation in which Abigail was herself a kidnapping victim, Nightingale reprimands her for striking a suspect by telling her "Abigail! That is not how we treat our prisoners!" The use of the words, "we" and "our" would seem to imply that in Nightingale's mind at least, Abigail is a full member of the Folly.