Like almost everything we do in aviation, this was a team effort.
The runway controller failed to react appropriately to the absence of gear as well.
Great if the caravan controller isn't confused by the Hawk nose light and spots you're gear up, but the blame for landing gear-up is very squarely with the driver! LOI is about as basic as it gets in an RAF cockpit. Not saying it doesn't happen, but please dont try to shift the blame! Furthermore, if you're doing an airtest then you must understand every aspect and potential pitfall.