This might prompt a little more interest in this thread:
In the UK, types used are in the majority MD 902 and EC135. There are a few A109s, a couple of AS365s, a couple of BK 117s and still 2 or 3 Bo 105’s around.
Except for in Scotland, all air ambulances are charity funded.
A few charities own their own helicopter and have contracts with established helicopter operators to provide the pilots and maintenance.
The majority of charities ‘wet’ lease the aircraft from an operator.
HEMS is single pilot with two medical crew on board (2 paramedics or 1 doctor/ 1 paramedic).
HEMS in the UK is daytime only, by NAA regulation.