If anyone suggested removing Addenbrookes or Great Ormond Street hospital from the NHS and running them as local charities I suspect the men in white coats would come round. Both these hospitals have serious charities that rightly or wrongly provide additional funding but they are core funded and managed according to NHS standards using NHS employed doctors and nurses under NHS control. Most air ambulance work is trauma which is a multispecialty service that depends upon the weakest link. No sensible clinician, starting from scratch, would allow a single link to be provided by a multitude of local charities and run outside the NHS. It is noteworthy the lack of peer reviewed audit and research about air ambulance work in the UK and the resulting lack of national guidelines and standards for the medical side.
I fully accept the high standards and innovation over the years from the aviation side but there is a difference between the NHS contracting in services it cannot provide (AOC, maintenance) and relying on a disparate provision. The charities have been fantastic and without them and public generosity we would have got nowhere. They should continue, but healthcare funding has moved on from the 1980s and air ambulance work should be part of UK healthcare in the same way as land ambulances.