And why exactly do police need to have guns on them at all times? Right, because each citizen they meet has a high chance of having one. In contrast, UK police don't carry guns. Let that fact sink in.
I'm not surprised. The UK police prefer to arrest people for mean tweets, and let the knife criminals run around Scot-free. Perhaps if they had guns they'd do their jobs properly (joke - they still wouldn't).
Police worldwide, where guns are usually illegal, are usually armed.