 She is a retired British police officer who was the first Chair of the National Police Chiefs' Council (NPCC) and the former Chief Constable of Thames Valley Police and Vice-President of the Association of Chief Police Officers (ACPO).She was the second consecutive head of the Thames Valley Police to move onto leadership of a national policing body; at Thames Valley she replaced former Chief Constable Peter Neyroud who, in January 2007, moved to the role of Chief executive of the National Policing Improvement Agency.Thornton was born on 27 December 1962 in Poole, Dorset.