British Bobbies have whistles but they also have guns!
the regular bobby does not have a gun.
only a small bunch of special squads of british police actually have guns.
Not all.
Most patrol without firearms. Some have firearms with them or in the vehicle.
“Armed police!”. . .upon arrival something those that are carrying have to say, if they have time, before they proceed with a call.
Red and white vehicles in London are armed police.