Motocyclist, betwixt glass and rim is exactly where my whistle was coming from.
Ah, I went for a run this evening and was going to tape that area up but I ran out of tape! I'll try that next. TBH though, it sounds a lot closer than the headlight.
I've had the dash out after this evenings run, looking for holes in the bulkhead but can't find any. I've now blocked all the gaps in the toolbox and also put some pipe lagging around the front wing stays, in case it's those, so ill have another run tomorrow to see if that has done anything.
It's loudest at 50mph, at which stage it's like someone blowing hard through a kettle whistle. Maybe the car is coming to the boil.
In response to other suggestions, it's not an easy up, it's a PITA hood (3 mins fastest up so far). And it's not the heater blower. Appreciate the posts though
Colin