Hi Steve,
Certainly potentially concerning - especially as many of us no longer fly with a map (2 separate GPS systems).
Not sure the CAA are technically ‘allowing’ the trials, as transmissions on these ‘licence exempt bands’ are the responsibility of Offcom - not the CAA, and the trials are obviously being sponsored by the MOD (presumably in the interests of ‘National Security’).
The incidence of this type of ‘jamming trials’ certainly seems to be very prevalent these days, so I guess we need to keep a good eye on the Notams to see when and where they are taking place, then make sure to take a chart and maximise eyes outside the cockpit for traffic whenever the trials are running.
Regards
Peter