The Metropolitan Police website: https://www.met.police.uk/

An article by Chris Williams (‘Britain's Police Forces: Forever Removed from Democratic Control?’) examines tension between the principles of local control and the direction of the police service by central government:  http://www.historyandpolicy.org/archive/policy-paper-16.html

History of the British Police: http://www.youtube.com/watch?v=9P48YT61zII. A 90-minute documentary charting the development of the British police from Robert Peel to today.