The absolute nature of the firearms legislation gives almost no room for manouevre. If you find a weapon dumped in your front garden, pick it up and take it to your local nick, you will have committed an offence and will be liable for a 5 year stretch. Arguments regarding whether it would be safer to leave the firearm in place (and risk someone else walking by and taking it) are irrelevant.
'Do you have a firearms licence for the firearm you are in possession of?'
....'No'.....
'You're nicked'.