to chase and approach a person who in your mind can trigger a bomb that will kill you and everyone around, Although I question the wisdom of shooting into the body as it could trigger any explosives, head shots are more dificult but safer. Unlike the US the suspect if it turns out to be a petty thief who made the unfortunate mistake of running from the law at a bad time, the Brits will never come under the scrutiny and civil suits it would engender over here.
thanx,
bill