The tricky bit here is that this is a civilian airport. Jamming GPS could reasonably be expected to cause significant difficulties for civilian planes and pilots. And thus passengers.
Much older. The basic "stack" uses radio beacons, not greatly different from early XX century tech. The more advanced Instrument Landing System is quite a bit more complex, but in very basic terms is a set of radio beacons that define a glide path. It is local, and requires no GPS.
Never mind that Aircraft will be under ATC in UK airspace, and ATC uses Radar + transponder to localise aircraft.
GPS is a navigational aid, not the primary navigation tool.