The answer, in short, is not very often. As Foreign Policy points out today, as of 2009 only 6,868 cops in all of England and Wales are even authorized to carry guns. Within London’s Metropolitan Police force, with about 33,000 cops on the beat, around 2,700 can carry a gun. And very few of those do so on a regular basis. The Bobbies apparently like it that way. In a recent survey, 80% of British cops said they don’t want to see all officers armed.
Shouldn’t they reconsider in light of the rioting? The police seemed simply outgunned and outmatched for several nights.