What’s the obstacle against downing illegally flown drones?

Well that isn’t exactly true either now is it.

Citing “well there was no photos” as a defence it didn’t happen is a bit of a crap defence.

Not an option with land border to UK

That’s incorrect. Mot having unlimited rights, is not the same as not having any rights.

If you built something overhanging a neighbours property at first floor level. They absolutely the right to that airspace and can have it removed.

I think the last stats I saw showed that 95% of those complaints were from a single person. He was averaging 80+ a day last year :)

Jamming isn't as precise as you think it is, it's noise covering the intended frequency and then some to stop any actual signals getting through. Those frequencies that drones use are the same range as most other commercial wireless stuff from wifi to Bluetooth use.

Jamming a smallish government building is one thing, it's a small area so overspill isn't too much of a concern and networking is probably all wired for security and they could avoid using normal commercial equipment where they did need radios something.

But an airport you'd need a huge area and then a few km outside, at a high strength to cover the airspace.

It is probably easy enough to down drones by jamming and find culprits if the culprits you are dealing with are clueless dopes just trying to show off or totally ignorant of what they are doing. You are probably dealing with cheap drones bought off Amazon.

But what about more sophisticated actors so seek to cause economic disruption. Drones are readily available that can fly autonomously along a pre-determined flight path without external radio guidance. A well organised actor intent on divelment, with some investment, could have one or more of these and give them flight paths that would take them in at a very low altitude before popping up once it reaches the airport and fly rings around the place to cause mayhem until either a) it is somehow taken down, or b) it crash lands or c) after wreaking its havoc, they fly out to sea to ditch a few miles off shore to lessen the chance of the drone being recovered. A drone or a small swarm of them could be secreted in a concealed location perhaps days or weeks in advance, and programmed to begin its flight at a pre-determined certain time.

What is the defence against that? I know there are microwave type devices that are capable of cooking a drones electronics to bring it down, but I doubt these are widely available to authorities.

Asking the Defence forces to shoot down a drone with bullets is not going to happen. Aside from the stray bullet issue, it would be next to impossible to hit a tiny drone with a bullet. You'd need some sort of Luftwaffe flak to get it, which is clearly a non runner.

As for regulating at point of sale. Pointless. ......

eBay, Aliexpress, amazon, Wish.

An Post seem to be doing a good job at customs at stopping anything even legit coming in!

If it is an EU wide rule, it would be fairly easy to enforce. All outside parcels are checked for customs paperwork.

Jamming mightn't be totally effective as I think more advanced drones can be pre-programmed with a specific flight plan and not require any real-time human operation.

Shotgun would be a good way. The only problem is due to the overcautious lefty gun laws here several new laws would have to be created before you could put a shotgun in the hands of a fella wearing a DAA jacket. Said fella would have to be sent on a training course costing many thousands and taking many months where they basically repeatedly tell him "only aim at drones and not passenger aircraft".

If you really wanted to cause trouble you could have a baloon hovering about 60,000 ft above the airport periodically releasing drones with the aim of getting them sucked into jet engines. Poor auld Leo would have to go begging the Brits to shoot it down.

There a good few videos of people testing shooting them with snipers and shoguns. The latter with special shotgun drone shells that have shot connected with wires like a net when fired. They all found it very hard to hit a hovering drone, even a static one. Basically it's not viable.