The Royal Marines of 43 Commando guarding the nukes at Faslane have loaded weapons.

The Security Forces at the base in question guard strategic nuclear weapons. The other USAF command most concerned is USAFE, where the threat of terrorism against a USAF facility is greater than in the mainland US.

Sure, there are scenarios. Article describes a classroom or briefing type situation though, it's holstered but on the desk. This is not someone on duty guarding anything.