Greenhalgh began his political career in the local politics of the London Borough of Hammersmith and Fulham, first standing for election in 1994 in Sands End, a relatively poor ward within Fulham. He was unsuccessful. In a by-election in 1996, he was elected to the Hammersmith and Fulham London Borough Council in the Town ward, at a time when the Conservatives were in opposition on the Council. Two years later, he became the Conservative spokesman on social services. Then, in 1999, he became the deputy leader of the Conservative group, and in 2003 the group leader, and in 2006 the Council leader. At the next elections in 2010, the Conservatives under Greenhalgh lost two Council seats but still retained a large majority. During his time on the Council, Greenhalgh became famous for being a cost-cutter, for which he has received both praise and criticism. In 2008, Greenhalgh was appointed by Eric Pickles, the then Shadow Secretary of State for Communities and Local Government, to head the new Conservative Councils Innovation Unit to formulate new local-government policy, and he was also appointed by the new Mayor of London, Boris Johnson, to oversee a financial audit of the Greater London Authority. In 2012, pursuant to section 3 of the Police Reform and Social Responsibility Act 2011, the Metropolitan Police Authority was abolished and replaced with the Mayor's Office for Policing and Crime. On 6 June 2012, Greenhalgh was appointed, by Boris Johnson, to head the MOPAC, as the second Deputy Mayor for Policing and Crime. Although Greenhalgh was not an elected official the Mayor was permitted to appoint an unelected official by sections 19 and 20 of the act. Greenhalgh resigned from his roles as Council leader and Councillor. In February 2014, Greenhalgh publicly endorsed Johnson's proposal to equip the police with water cannon to be used in the event of a serious outbreak of public disorder. However, the water cannon bought by Boris Johnson for £322k were sold for scrap for just £11k having never been used after the police were banned from using them by the Conservative Home Secretary. In December 2014, Greenhalgh became the third declared candidate for the Conservative Party nomination in the 2016 London mayoral election. On 18 March 2020 he was appointed an unpaid Minister of State jointly at the Ministry of Housing, Communities and Local Government and the Home Office.
Greenhalgh caused controversy when police were handed a dossier arguing that between late 2010 and the summer of 2012 officers of the council he headed had promised an "early movers list" or "VIP list" of residents preferential treatment in the allocation of replacement homes if they gave their backing to the estates' being knocked down. The dossier argued that offering such inducements would amount to the offence of misconduct in public office. Greenhalgh was also the subject of controversy in the first months of his appointment as the Deputy Mayor for Policing and Crime. He apologised after a colleague stated that he had patted her on the bottom, though she apparently did not make an official complaint, and he stated that he had no recollection of the alleged incident. He sacked both the MOPAC Chief Executive and Deputy Chief Executive, with both of them being subject to non disclosure agreements. He also had difficult relations with members of the London Assembly. However, Greenhalgh has also been the subject of praise. The Daily Telegraph has often named him among the "Top 100 most influential Right-wingers". He ranked 88 in 2009, 71 in 2010 and 84 in 2011. ConservativeHome named him the "Local Hero of the Year" for 2007/2008, after having received 8000 votes for him from the website's readers.
Personal life
Greenhalgh is married with three children and lives in Fulham. His interests include motoring and tennis. He speaks French, German and Italian. Since 2006, he has been a Trustee of the Carmelia Botnar Arterial Research Foundation and since 2012 a governor of Hurlingham & Chelsea School.
