Allison (left) during a visit to the Olympic Stadium in 2011
Allison joined the Metropolitan Police in 1984, initially serving as a constable in Walthamstow, and was promoted through the ranks. In 1996 he became a Chief Inspector at Hammersmith, where his responsibilities included the policing of Queens Park Rangers F.C. matches.[1] He served as staff officer to the then deputy commissioner Sir John Stevens between 1998 and 2000. In 2000 he was appointed Divisional Commander at Paddington, and was promoted to Chief Superintendent in 2001.[1] In 2002 he was promoted to Commander, and appointed Borough Commander for the City of Westminster.[5]
In 2008 Allison was appointed temporary Assistant Commissioner with responsibility for Central Operations, replacing Tarique Ghaffur when he stepped down.[9] He was appointed Assistant Commissioner in May 2009, and given responsibility for planning the policing of the 2012 Olympics.[10] He held this position until the end of 2010, taking up a full-time role leading security for the Olympics in January 2011.[11]