I think the AAIB is infected with the same attitude against GPS as some in the CAA. Old retired airline pilots and ex Military navigators, with little operational knowledge of the subject.
Personally I would not stray far from my base in the London area without GPS, in anything other than good VMC, for the enhanced situational awareness it gives.
The recent advent of cheap, IPad based, GPS moving map displays is one of the greatest navigation airsafety advances in recent years.