Hamish <<...it wasn't that the engines had not yet spooled up to max speed, it was a matter that the FADEC had not responded to the pilot's request...>>
What was this based on? Was this formally put to the AAIB?
Given that helicopters are inherently unstable and that such control systems would be working all the time, it seems highly improbable that the FADEC either didn't respond just at that moment before impact or that the crew did not notice such a problem earlier and avoid approaching difficult ground – they had flown quite a distance that day with it apparently working!.