Police service records and Court and Criminal records
most of these need a visit to TNA(PRO) at Kew The National Archives
History by the Yard History by the Yard - http://www.historybytheyard.co.uk/
Police Roll of Honour Trust - http://www.policememorial.org.uk/
The Proceedings of the Old Bailey, 1674-1913 http://www.oldbaileyonline.org/