that area of london would have had Armed Officers walking around on patrol and they have a massive amount of trained officers ready to use arms, the ARU in central london is a fair size
Now imagine something similar happening in a sleepy small town in Gloucester or Somerset, the ARU might take 30 mins to arrive on the scene and then it will likely only be 6 of them, think of the damage someone could do in 30 mins
a scary thought
i know the government has said they are training up more AR officers, but not enough and not fast enough