NFR terrorists in Westminster.

[YankeeJim]

Guns have to be a last resort, why not stun guns for policeman in vulnerable locations.

Actually, stun guns & bean bag rounds are standard equipment in most police departments and are deployed on a regular bases. It should be noted that these are usually used in standoff situations. If a person is waving a gun around, the police don't use them for obvious reasons.
Surprisingly to me is that statistics on police shootings vary somewhat. I did see one that the FBI says that there are approximately 390 people killed each year on average between 2000-2014 by the police. That in a nation of 320 million. Compare that to the city of Chicago where there were 762 people killed by guns in 2016 alone. If you take Chicago, Detroit and Baltimore out of the mix, US gun deaths are not much different than other industrialized nations. Also note, that the three cities I listed all have some of the strictest gun laws in this country  and none are in the "gun tottin" west.

[Holders]

I think that the balance is right here now. Only those who are suitable mentally, technically very competent - and are prepared to do the job - get to carry weapons. If all police were armed, the level of training/competence would inevitably be lower, there'd be higher risk of an element who'd shoot inappropriately or even hesitate to shoot when they should.

The Westminster attacker was killed by a body shot but police have been trained to shoot to the head when required, e.g. suicide vests. I researched that 7% of London police are trained; that seems a little low to me but perhaps it's enough. Of course they should be armed when on duty at vulnerable locations, e.g Westminster, airports etc but a river bridge would hardly be classed as that. And, yes, in my view with hindsight the cop on duty in PC Palmer's position should have been armed but one must still wonder if he'd have been able to react quickly enough to defend himself from an attacker with a knife when he sees hundreds of friendly tourists a day and some even wanted "selfies" with him.

On a day-to-day basis around the country in general they don't need to be armed.