I would venture to suggest that there is another more fundamental issue at play, which has not really come out despite all the discussion here and elsewhere. That is the alleged failure of ATC to reply to initial calls or perhaps on other occasions the curt 'remain clear' or 'standby' that many of us are familiar with.
I think most private pilots must understand that controllers on a 'quiet' frequency might be busy elsewhere, especially with the military who have UHF frequencies as well. But do controllers fully appreciate the converse, the tension escalating in the cockpit as some boundary approaches? In some cases the pilot will have doubts that his call has been heard, that he has the right frequency (the rate of change of frequencies is considerable) or that his radio is functioning. All the time the boundary is approaching and options are reducing.
Because there is a definite habit (In my opinion) of putting private pilots on 'hold', some pilots might have a tendency to conclude that the controller is playing 'chicken' and continue inbound where otherwise, they might take a different route.
In my experience, a polite reminder often produces an instant clearance, leaving one to wonder why the clearance or at least a 'continue inbound' had not been forthcoming immediately.
Would it be possible for someone in ATC to look in to this issue of what I might call 'delayed response'? If the controllers are really too busy to respond immediately, are there safety issues with the workload and the traffic that they are handling? And if not, is it possible that there is in some cases a culture of 'private pilots can wait' that could be improved by a little education?
I would like to add that I am not any way 'knocking' UK ATC who in my experience provide an excellent and friendly service and doubtless have their own completely justified opinions regarding 'amateur' pilots. It's worth adding that similar situations arise in the USA and that Class 'B' controllers in my experience occasionally play a very similar tactic regarding 'cleared to enter class B' right up to the point where one would have to make a 180.