I believe the time has now come for police to be armed. Crime has increased dramatically over recent years. However, this should be combined with harsher and mandatory penalties/punishments for those that commit criminal offences. Current penalties do not deter.
Those carrying guns, knives and other deadly weapons in public, (unless authorised) should serve a minimum 10 year prison sentence (And that should mean 10 years, no time off for this and that). Anyone using a gun or other deadly weapon, whether to harm, kill or just threaten others should receive an automatic death sentence. That of course requires the reintroduction of the death penalty, which hopefully will be by referendum sooner rather than later.
Lets not just stop with the UK. Much harsher penalties needed nowadays here in Thailand!
For the record, I was threatened with a gun by a crazed Thai man who rented property close to my house some 30 years ago. He thought I had killed his chickens. Thai police did nothing other than instruct the property owner to evict him and his chickens. Heard he got run over and killed by a bus a week later in Bangkok! Justice served!