The "best available" evidence i.e. studies done by the health establishment, suggests that the benefit of HEMS ops are marginal. Ambulance drivers or ex ambulance drivers (who usually figure large in the managment of ambulance trusts) usually see the HEMS as a threat to them too.
The Surrey situation is worse even than other trusts. If the Berks HEMS is used in Berks, then it is paid for by charity (except for the paramedics). If a HEMS is used in Surrey, then the Surrey Ambulance outfit gest charged for the FULL cost of the flight.
One of the paradoxes of fund raising for HEMS seems to be that the richer areas have more difficulty in fund-raising