There was a news item on earlier that showed a jammer manufacturer who displayed a jammer in operation. It only affected the drone & would only require 2 units for the size of Gatwick (3 for Heathrow)
IIRC it is only designed to affect drones using certain frequencies.
It won't do anything for drones that are pre-programmed, drones that use things like mobile phone frequencies, drones that use non standard frequencies.
So it basically won't stop anything other than the cheaper off the shelf models as the more expensive and custom ones tend to have things "auto pilot" functions or GSM comms, and auto pilot based on GPS can't be blocked at an airport without the side effect of you know, shutting the airport down, whilst blocking mobile phone frequencies is not going to happen because those are needed for everyone from the general public, to the site security and service staff to the police (whose "radios" IIRC are now basically mobile phone based).
Even for those frequencies it does work on it may not have approval for use in the UK in general, let alone around airports (as the frequencies drones use tend to be ones allowed to be used by other devices)
There is no simple, safe and effective way to stop drones from something as large as an airport's airspace, as you need active measures to deal with them and that basically means enough staff/equipment to cover some very large areas and get to any point in that area in seconds/minutes with the deployed counter measure otherwise the drone can just disappear again (so potentially dozens/hundreds of "counter measure" drones placed not just at the perimeter but at various points so no part of the airport is more than say 30 seconds from one regardless of if it's the perimeter or the middle of the runway).
Even smaller areas like Prisons have problems with stopping them, and they at least have the option of putting netting up over the main parts of the facility.
