Rotational brake creak

I’m completely stumped on a problem with my rear left brake.

At low speeds I can hear a creak, under braking, which is relative to the speed at which the wheel is spinning.

I have installed new pads, a brand new caliper and also cleaned and re-greased multiple times. After installing the caliper, the noise seemed to disappear for a couple weeks but has just re-appeared yesterday.

I also swapped the discs round to make sure it wasn’t that but seemed to still be coming from the same side.

Any ideas?

It’ll be runout in something. If you think that you’ve eliminated the discs then it could be the hub. Have you got a DTI to measure it?