Sir John has served for 42 years in the Police Service. He commenced his career in the Metropolitan Police where he was involved in a range of activities from leading successful murder enquiries and leadership of crime squads, commander of the busiest CID office in London to the hunt for a major spy (George Blake). During a second tour at Heathrow Airport as Detective Chief Superintendent he was responsible for the operation which used covert micro optics in both aircraft holds and handling bays, this resulted in the arrest of half of British Airways handlers in one operation. Extensive administration experience was gained in a two-year period as staff officer to the head of London CID.

In 1986 he was appointed Assistant Chief Constable of the Hampshire Constabulary with responsibility for personnel and training. Two and a half years later he was appointed Deputy Chief Constable in the Cambridgeshire Constabulary with responsibility for discipline, policy and strategy, personnel, finance and administration.

In September 1989 he was appointed to enquire into breaches of security by the Security Forces in Northern Ireland known as the Stevens Enquiry. It resulted in 43 convictions and over 800 years imprisonment for those convicted. The subsequent report in 1990 contained over one hundred recommendations for the handling of security documents and information. All of those recommendations were accepted and have been implemented. The enquiry has been praised by the Secretary of State in Northern Ireland, the Police Authority in Northern Ireland, the Chief Constable of the Royal Ulster Constabulary and the Irish Government, amongst others. At the request of the Northern Ireland Authorities, this enquiry continued into Stevens II and now Stevens III and has now resulted in 98 convictions and further recommendations.

In September 1991, he was appointed Chief Constable of Northumbria Police where he implemented a total restructuring of the Force and crime reduction policies, which resulted in an over 42 reduction in crime over five years, results never achieved before in British policing. He was Chairman of the ACPO Crime Prevention Committee, the Behavioural Science Committee and Advisor to the Forensic Science Service. In October 1996 he was appointed to conduct an enquiry into the National Criminal Intelligence Service involving the corrupt misuse of telephone tapping intelligence. As a result he made 98 recommendations, all of which have been accepted by Her Majestys Government and have been implemented. In September 1996 he was appointed one of Her Majestys Inspectors of Constabulary with responsibility for the North East, the National Crime Service, the National Criminal Intelligence Service and national responsibility for crime.

Sir John was appointed Deputy Commissioner on 1 May 1998 and led the fight against corruption. He took up his post as Commissioner on 1 February 2000.

He has been Patron of a North East Charity since 1992, which has built schools and care centres for mentally and physically handicapped children. He is also the creator of Convoy 2000, a charity set up to improve the quality of life for Romanian orphans, Aids sufferers and disabled children. He was awarded the Star of Romania by the President of Romania and the Rotary Paul Harris Fellowship for this work. He is Patron of the Greenwich Community Safety Trust, the Northumbria University Community Safety Research Unit and The Security Institute he is also Patron of the Thessaly Community Centre in Battersea.

He holds an Honours Degree in Law, a Masters Degree in Philosophy, is a Doctor of Law and an Honorary Doctor of Civil Law. He is a Fellow of Wolfson College, Cambridge, and was visiting Professor at City University, New York and a member of the directing staff at the Police Staff College, with special responsibilities for legal topics and crime. He assists and advises the South African, Jamaican, Bulgarian, Romanian, Qatar and Greek Governments on policing. He has a wide interest in sport as a spectator and a participant. He holds a multi-engine and single jet pilots licences.

He was knighted in Her Majestys New Year Honours 2000. He was made Deputy Lieutenant of London in 2001 and a Knight of St John in 2002. Sir John was awarded the Freedom of the City of London 2002. He was also awarded the Queens Police Medal for distinguished service in 1991 and during his career has been commended on 27 occasions for outstanding detective ability or courage.