New Tricks is a British television police procedural, created by Nigel McCrery and Roy Mitchell, produced primarily by Wall to Wall (until its final year, when it was handled by Headstrong Pictures), and broadcast on BBC One. The programme originally began with a pilot episode on 27 March 2003, before a full series was commissioned for 1 April 2004, with it concluding after twelve series on 6 October 2015. The show utilises an ensemble cast, of which Dennis Waterman was the only constant over all twelve series; this cast variously included Alun Armstrong, James Bolam, Amanda Redman, Denis Lawson, Nicholas Lyndhurst, Tamzin Outhwaite, and Larry Lamb.
The series focuses on the work of the Unsolved Crime and Open Case Squad (UCOS) – a fictional division within London's Metropolitan Police Service tasked with re-investigating unsolved crimes. UCOS primarily functioned with a senior police detective overseeing the work of three retired police officers who would handle each case, and who could bring in police support when needed. Each episode focuses on a different investigation, with characters often coping with problems at their age but using their wisdom to overcome hurdles in the original investigation of cold cases. Both creators, McCrery and Mitchell, devised the title of the programme around the proverb "You can't teach an old dog new tricks".