Hi, Not the answer to your question, but the only time I heard a police whistle used in anger during 39 years service, was in 1960, Maidstone, Kent, dead of night, no traffic noise, blasted off about 800 yards from myself. In those days we had 7 town centre beats each manned, and it was amazing where each of the officers emerged from and impressive to see 8 officers in total converge on one angry tramp and an even angrier Constable, whom he had assaulted. Sean