Questions regarding shooting

Hello,

forgive me if this sounds really dumb. But I have a few questions i’m hoping you guys would be able to answer. I’m a Police Officer but haven’t had the opportunity to speak to someone on guard duties.

1. When you’re on say buckingham palace, are the guns you carry loaded?

2. If so, or at any point your guns would be loaded in the UK, what would happen if you were to shoot someone? Not necessarily terror related as such. Say you see someone stabbing another? Are you allowed to shoot? Law states you can in saving life and limb but it’s not something i’ve thought about before from your perspective.

Would you be under investigation? would it be lengthy like ours?

Cheers