Re: Shotguns?
"good luck storing a 24 pounder in the mandated gun cabinet"
Good luck to the police in removing said cannon when they are directed to where it's stored (chained to the garage rafters, the back wall, the side wall and locked inside a brick outhouse as the one I helped crew was kept). Funnily, the officers who attended that call saw the funny side and just nodded and called it in as 'secure'. The ones who went to check one musket, however, were somewhat confused and then baffled as to why bother: The cabinet was bolted to the back wall of an Air Force Armoury, behind locks, armed guard and past the rather modern firearms that were not licensed through the police...
"Tony Martin"
To clarify: He was charged with murder (reduced to manslaughter) for shooting and killing a burglar with an illegal shotgun (A pump action shotgun of a type not allowed in the UK, even with a license) when he'd already lost his shotgun license (he lost his license in 1994, killed the burglar in 1999). The police claimed he was lying in wait for the burglars, and the man he killed, he'd shot in the back while the man fled the property.
"Hells, our terrorists aren't generally armed with more than a carving knife."
With which they can be quite effective, although they also use cars, bombs and other impliments. Just not generally guns.
"Suffice to say that blowing away drones with a shotgun is not likely to happen over this side of the pond."
Well, not firearms at least. Not sure how effective a Nerf gun would be, but a paint ball gun might do some damage. Flip side, there are always arrows (if you're any good with a bow), fishing line (as has been suggested) or other impliments, although this being the UK, good old fashioned weather (rain, gusty winds etc) makes drone flight somewhat of a gamble.
Rain... wonder if a super-soaker would hit a drone? That could be an alternative if it could fry the electronics... how do drones fare when soaked?