The thing is, people in big cities, especially London and especially this particular location, are on 'alert' at all times since the risk of terrorism is 'severe'.

It must be frightening to have this happen nearby and wonder if a bomb is going to explode at any minute.

It makes me think of poor old Trump recently when someone shouted, "Allahu akbar!" and he nearly weed himself with fright.

My personal guess (can't really tell as not enough info yet) is that this chap is merely a miscreant known to the Police and under the influence of drink/drugs. But seeing the pics of Police officers standing about holding those automatic rifle things is very sad.