Carrying around a deadly weapon is always a risk

Which is why our officers are trained.

Someone could steal a cops gun and go on a rampage

This isn't the movies. Holsters have very specific security features to prevent a random guy from removing the gun from the holster.

The only person who could possibly steal a cop's weapon is a person trained in firearms with knowledge (and experience) using a police holster.

Instead of pointing to Britain, why not focus on how Canadian officers are using or misusing their firearms and at what rate they are appropriately being used to see if the rate of abuse is high enough to warrant blanket changes?