Getting back to the debate a wee while back; the 'open cockpit' description comes from the CAA (I believe) and prohibits the crews carrying certain medical cases. I may be incorrect in this assumption though. There is a distinct difference from contamination with bodily fluids, a common problem for all SAR aircraft, and contamination with an airborne virus/bacteria. Transfer from the IoW by air is 5 mins, but on a ferry it's less than 30 mins. I could understand the necessity to go by air if it was from Barra, or a rig or the Isles of Scilly, but an ambulance on a ferry across the Solent ain't that bad.
The AW189 has a partition from the cabin (similar to that found on a London Black cab- the jokes have already started ".....you never guess who I had onboard last night, guv'nor), due to a CAA requirement in order to use NVG in the cockpit. or so i believe