Been using the Aero again today for the first time in a few weeks. The warbly noise is still there. Peaks at around 45mph then goes quiet again, but is apparent again, sounding the same at above 60mph. It is there whether accelerating, decelerating, or even coasting in neutral/clutch down. It is there when I turn the climate off and set it to recirc.
I've noticed also there is a much broader rubbing noise that sounds the same as when the rear brakes were binding on my son's Focus. He needed a new caliper, but both my front calipers are refurbed (by Bigg Red) bigger Aero brake calipers which were fitted with new discs and pads at the same time, and haven't done that many miles.
Both front discs look fine and I can't see any evidence of excessive brake dust on the front alloys. They don't feel too hot after driving either. The car is braking fine and there is no brake squeal.
The only other thing I can think of is maybe a wheel bearing is shot, but both fronts were done a handful of years ago (and not done excessive miles since). I do believe the front dampers and top mounts do need doing. One of the dampers has had a misting of oil on the last couple of MOTs, and the car has had a front suspension knock since I bought it in 2017, but has never been highlighted in any service or MOT. It has been on my list to get the dampers and top mounts done for a while, but the long running traction control fault saga put it on the back burner!!!
Could it be that knackered suspension mounts etc could be transmitting noise into the body that would not otherwise be there?
Or might there be a driveshaft issue?