DFC
Is your post really the official view of the CAA? Do you work there?
"However, when completing the NDB approach everyone constantly monitors the ident because there is no warning of failure"
Actually, receiving the audio ident means nothing, zero, zilch, nowt, nothing whatever about whether the NDB is indicating anything meaningful whatsoever. All it tells you is that the the part of the circuitry that receives and demodulates the AM ident works, and the unit is tuned to the right frequency.
Same incidentally applies to a VOR. I've flown with dead VOR receivers (in "VFR" school aircraft) which idented just fine.
Whereas a GPS will detect if it isn't getting a solution from the received signals. There is also RAIM.
If what you wrote is really the official view of the CAA, they need some education on how radio works
It is true GPS can be jammed. Then one would not do that approach. Same with DME packing up; one cannot do a "DME mandatory" IAP. Any gizmo can pack up, anytime. Loads of GA planes have duff DMEs or duff ADFs. So instrument flying should be banned unless one has two of everything.
Finally, does the CAA know something the FAA don't?