Education
He rose to the rank of commander in the MPS.
He rose to the rank of commander in the MPS.
He was appointed on 11 May 2009 and retired on 31 July 2012. O'Connor's police career began in 1968 as a constable with the Metropolitan Police Service. He left in 1970 and rejoined as a graduate entrant in 1974.
In 1985 he was appointed as a Superintendent in Surrey Police and returned in 1988 as a Chief Superintendent to the Metropolitan Police Service. In 1991, he was appointed as an Assistant Chief Constable with Surrey Police before transferring to Kent Police where he was appointed as Deputy Chief Constable between 1993 and 1997. In 1997, he became a Metropolitan Police Assistant Commissioner and from 2000 until 2004 was appointed Chief Constable of Surrey Police.
From 2004, he was one of Her Majesty's Inspectors of Constabulary, and became Acting Chief Inspector on 1 December 2008. On 28 March 2012 the Home Secretary announced Sir Denis would retire on 31 July after more than three years in the role. He is trustee of the Surrey Care Trust in Woking Surrey, which provides education, training, skills and volunteering opportunities to those who need motivation or a second chance in life.
The charity also runs a fund to help those facing hardship throughout Surrey. Adapting to Protest published 7 July 2009. This report concerned the policing of the 2009 G-20 London summit protests.
Stop the Rot, published 24 September 2010, that examined the effects of anti-social behaviour and the withdrawal of police street patrols. According to the Stop the Rot report, it confirmed the widely held belief by UK people, that the police had largely retreated from policing anti-social behaviour on the streets, by grading calls and not replying to incidents deemed to be below a specific grade of offense. The results was a rapid increase of yobbish behaviour in the last decade.