Whining noise when car is moving

[OscarG]

Hi Chaps, wonder if I can pick your brains. I have an old (2001) but low mileage (62k) Saxo 1.1i that's very recently developed like a throbbing /whine sound. It almost sounds like wind noise when the car is moving. At first I thought something was stuck in a wheel. The pitch/tone goes up and down related to speed. It seems loudest between 40-50mph, at lower speeds can't hear it.

I've tried revving the engine parked up in neutral, no noise. Only happens when I'm moving.

I haven't yet tried depressing clutch and putting in neutral when driving along, I've read that might determine if it was a layshift bearing in gearbox.

I've watched a load of "wheel bearing noise" vids on youtube but haven't heard one that sounds like mine.

The car drives absolutely tip-top, doesn't vibrate, brakes seem ok. Its had 2 new tyres and a service 6 months ago.

What do you think it could be? Do you think it's safe to drive?

Thanks for your time!