That’s an easy one. Thorney Island is no longer considered an active uk airfield. Nor has it been for some years.
It continues to be assigned two ICAO codes (one military, one civil) EGUV and EGYT. But these don’t appear in any current listings.
List of airports in the United Kingdom and the British Crown Dependencies
Without checking every entry, I believe the only airport’s that gain FRZ status are those on NATS’ UK AIPs (Aeronautical Information Publications) …
Aerodromes published in the UK AIP
Thorney Island is in blue/yellow in the above maps because of its military status.
But, coming back to the crux of the issue, there is (and always had been) a mismatch between DJI zones and UK legal restrictions.
Chances are this goes back to DJI implementing a global policy of safety rather than matching local legislation in every detail.
The current DJI Geo Zones, that include the rising base in line with runways, were implemented globally … but there’s no way every county is doing the same thing as far as local legislation.
I doubt DJI’s Geo Zones will ever match local requirements, either, since updates would be so frequent as to piss off everyone. Whenever they updated for any country, everyone in the whole world would need to update.
Perhaps they could introduce a country-by-country update system. But I can’t see that being implemented retrospectively to existing products, and the cost to them going forward to accurately maintain for all countries would be a hugely expensive.
So, I reckon were stuck with their simplistic global approach that will tend to ignore smaller airfields (Chichester/Goodwood) and impose a generous protection (cynically, to their name more than aircraft/passengers?) around larger airport’s with scheduled flights.
One of the issues with them extending their coverage to smaller airfields (and let’s not forget this would happen globally, not just for little old UK) is data/memory. It all has to be stored in the drone’s memory. Who wants to pay for a recreational drone where (perhaps) 25% of the cost becomes the physical inclusion of adequate memory into the drone to store, and the financial burden of creating/maintaining/delivering, a global database for every potential hazard? Our drones would end up with more of such data than an Airbus A380!