The guns were in his bag along with the knife, if he had them out and waving them about there would of been two probable outcomes
A ) shot by Firearms Oficers
B ) arrested by Firearms officers and charged with S19 Firearms offence -
Offence: A person commits an offence if, without lawful authority or reasonable excuse (the proof whereof lies on him) he has with him in a public place
a loaded shot gun,
an air weapon (whether loaded or not),
any other firearm (whether loaded or not) together with ammunition suitable for use in that firearm, or
an imitation firearm.
Now having it in your bag because you were moving house/going to a skirmish/ going to a friends to take it to bits would be seen (hopefully) as reasonable.
Having it exposed in public using those same excuses would most likely end up in arrest or 5.56 keyhole surgery.
Edit: Removed the smily , which was kind of undermining my point