I walked to work this morning through a park in Central London. It was a typical scene. There were commuters, walking briskly on their way to work. There were a couple of joggers showing an enthusiasm for exercise in the morning that is completely alien to me. There was the token wino, sitting on a bench, contemplating life. There was also a hyperactive photographer, snapping Buckingham Palace and causing congestion amongst the pedestrians as he tried to take his photos.

And I saw a couple of police officers. Both wearing stab proof vests, one carrying a rifle, the other with a handgun strapped to his side.

I didn't bat an eyelid. I did not even consider it in anyway wrong that I was looking at two heavily armed police officers strolling in the park at about 8am. To me, that sight was completely normal. Even though, as our police force isn't armed, it shouldn't have been.

So my question is this. When did it happen? When did it become normal for police officers in London to wander around carrying powerful rifles?

Answers on a postcard to the usual address. Or failing that, in the comments section.