Cabby, my understanding is that they need airport standard landing aids and traffic control in the dark. There are no other 24/7 options that will accept a tiny P68 mixing it with the big boys. Both the Dutch and the Belgian police proved that big airports are fraught for light police aircraft (albeit Cessna singles) when operating from Amsterdam and Brussels.
Last chance saloon may be somewhere not too major like Teesside.
It seems Gama engineers are moving to North Weald because the hangar there is the same size as the DSA hangar.