I remember an incident back in the 60's in Southend during the time of the Mods and Rocker troubles, two rival groups were shouting abuse at each other across a car park in the middle of which stood two coppers gossiping away with out a care in the world while their dogs sat at their sides. A sargeant arrived and through a bullhorn proceeded to tell the gangs to disperse a request which was met by a barrage of abuse from both sides, he then gave an order to his two cops who each advanced to about twenty yards from the respective gangs. They stopped, unleashed their dogs and stepped back a pace.The dogs just sat there the crowd dispersed.