I thought longarms had to be stored at the local constabulary and signed out for use?
Firearm Laws in the UK
“The police will inspect where you plan to store the weapon and advise you on what they require you have for the firearm to be safe. The Firearms laws state your guns must be safe from theft. The normal method of security is a locked cabinet that is carefully secured flush to a supporting wall, to stop it being ripped down.”
I’m not familiar with that law, but know permitted arms MUST BE STORED in a SAFE BOLTED TO the floor and wall.