Relax, Morbid -
British yoots (I believe they refer to them as "chavs" over there) do not, for the most part, carry firearms. That is left to their elders, and only a small number of them at that.1
Chavs carry cricket bats, automobile radio antennae (when they can find the long ones), and until recently banned, knives.2
They have become almost uncontrollable ever since two events took place: first the introduction of the Anti Social Behavior Order (ASBO); and second the case law ruling that citizens defending themselves agains the predation by using any force against them are guilty of the more serious crime of assault.
Because the British subject may no longer defend themself, they must call on the police. Because the chavs have a history of not only refusing to obey the orders of the traditional, unarmed, Police Constable it has become necessary to find something the chavs will fear if not respect.3
1 - I know! Even if only one criminal had a firearm and used it in their crimes, it would be one too many when you are the victim facing that firearm.
2 - Ever since (f)GB banned all sharp and/or pointy cutting impliments this has been less of a threat. But you still might receive a serious bruise if attacked with a butter knife.
3 - My money is on the armed team from CO19 have a set of Rules of Engagement that prevents them from actually shooting anyone. However, that is not a sure bet - the level of frustration expressed by the folks on the street and in Parliment has of late been increasing by leaps and bounds.