I'm not going to ignore a UK CAA document cos some guy on PPRuNe says so.
Which is entirely your perogative, however your previous posts were ethusiastically trying to convince the rest of us that it was against the rules to use a GPS as primary navigation equipment when I clearly pointed out that in order to meet BRNAV and PRNAV in light aircraft a GPS is the only means of complying. Therefore it is somewhat at odds about your claim that you are not allowed to use GPS as primary navigation.
As IO540 quite rightly points it there is no legal requirement for any type of PRIMARY navigation. The CAA safety sense leaflet is primarily aimed at those who think it is a great idea to use a car or walking GPS or the in the bottom of the bag brigade who generally don't have a clue how to use them and when they actually need them do more harm than good.
The use of an aviation GPS even a handheld one for VFR flying if properly trained for and used is a huge benefit to situational awareness and safety. It can be used on its own or if the pilot is prudent as a part of blend of navigation tools.
For IFR cruise and approaches then an approved panel mount is the way to go and used by the majority of GA IFR traffic this day. Even our work Turbines are being fitted with Garmin stuff now to replace the old FMS. The FMS was also the PRIMARY means of navigation for us in the past, however it is not unknown for me to stick the 496 up on the dash to watch the world go by.