[2] In March 2000, as a Detective Superintendent, she was appointed head of the informant unit in the Criminal Intelligence Branch (SO11) at Scotland Yard.
In January 2005, she joined the National Crime Squad as Assistant Chief Constable in charge of covert policing and served there until her appointment to Merseyside in 2006.
Gallan later became head of the Metropolitan Police's Directorate of Professional Standards and was in charge of Operation Alice, an investigation to look into allegations relating to the "Plebgate" affair.
She told The Guardian that “children are not born bad” and wants to address inequalities that lead to people feeling, “they do not have a stake in society”.
[5] Gallan was played by Sara Powell in ITV's 2017 drama Little Boy Blue, which is based on the murder of Rhys Jones.