I've got the sedan.

Caliper seems fine and braking doesn't do anything to the noise but will try the new one when it arrives anyway.

Also just ruled out the abs sensor which was cracked so I'm not seeing any more possibilities at the wheel, unfortunately.

have you checked the none of the handbrake is rubbing on disc?

have you put car on stands [with axles in & all connected] in gear idling to hear where the noise is??

It's not the handbrake, as I removed it and went for a drive.

I haven't had it idling in gear on stands but the noise at that speed is not noticeable. It's only when I accelerate a bit that it can be heard. When I let go of the accelerator the noise immediately reduces by about 90%. It may even be my imagination that it continues at all without the accelerator depressed but I do think it's there just a lot fainter.

When you say that you removed the handbrake, what do you actually mean?

Did you just disconnect the cable or did you remove the shoes?

Remember that the EF/EL/onwards use a shoe type handbrake setup that uses the internal drum part of the rear disc. If there is binding or over ajustment you will get a noise from the rear.

Have you checked the condition of the discs/pads?

I removed the shoe from that side, so definitely not that.

disc looks ok to me, no unusual scratches. pads look ok. a bit old but plenty of meat. will remove them tomorrow and put a spacer in and go for a drive. will also swap over caliper as replacement arrived today.

I did a diagnostic thing on autozone website which suggested uni joints or pinion something (flange?), which they said may be too low and therefore at the wrong angle.