Sir Paul joined Lancashire Constabulary in 1975 and was appointed to the rank of Superintendent in February 1988. Following a post in research and development he took operational commands in Lancashire
and Northern Ireland with the Royal Ulster Constabulary.
He was appointed Assistant Chief Constable Merseyside Police in October 1994, with responsibility for Territorial Policing Operations. Professional Standards, Marketing and Communications. His time on Merseyside saw him leading in areas of significant organisational change and high profile operational challenges, including the reduction of gun crime, anti-corruption and combating terrorist activity. He also negotiated the formal arrangements governing the provision of assistance by the Security Services to the policing of serious and organised crime, following the enactment of the Security Service Act 1996.
On 1 May 1999 he was appointed Deputy Chief Constable Lancashire Constabulary, responsible for the operations and operational support portfolios. He led the constabulary on strategic development including constructing the organisation's response to Best Value, crime reduction and its development of problem oriented policing, successfully embedding it within the police culture of Lancashire and he remains an affiliate of the Centre for Problem Oriented Policing in the USA.
On 25 July 2002 he was appointed Chief Constable of Lancashire Constabulary, responsible for an organisation of over 5,600 staff and the provision of policing services to one and a half million residents and visitors. During this time he was the Chair of the Lancashire Criminal Justice Board and the Lancashire Strategic Partnership. The force consistently achieved a place in the HMIC top tier of UK police forces and reported record falls in burglary and rising police numbers.
During this period he was also the Association of Chief Police Officers lead on Crime, working nationally with a number of key stakeholders to coordinate professional advice and guidance on crime related issues to the police service and it's partners.
On 16 March 2005 Sir Paul was appointed Deputy Commissioner of the Metropolitan Police Service. His role includes the function of Chief Operating Officer and in particular oversight of strategy, organisational performance and diversity.
In March 2007 Sir Paul was appointed to the board of the National Policing Improvement Agency.
Sir Paul was awarded the Queen's Policing Medal for services to policing in May 2000 and he received a knighthood in the Queens Birthday Honours List of June 2008.
On December 1 2008 Sir Paul became the Acting Commissioner of the Metropolitan Police Service.
On January the 28th 2009 Sir Paul became Commissioner of the Metropolitan Police Service.