Sas, that is 1 accident total and I think that aircraft was on police not HEMS duties at the time.
There will be more night HEMS in the UK so we will see what happens but the BIG difference is that the operators are not looking to make a profit - they are funded by charities and will have fully instrumented aircraft, autopilots, 2 engines etc etc - in short, all the things that are not mandated in the US.
I know it is an unfair comparison but the USA is the country with an apparently unsolvable problem with HEMS crashes.