Grinding in reverse from rear wheels

[Shel]

Hi guys.
Had the x5 parked up for a few weeks. Gone back to it and whenever it is reversing there is a loud groaning/grinding noise coming from the rear right wheel.
I've been messing about with it trying to find out what is causing it. So here is what I've found so far:
1. No grind in drive or forward motion
2. When reversing with handbrake applied slightly the noise goes away
3. Regardless of whether is in reverse or neutral any backward motion causes the noise. So that rules out any trans issue.

My gut is telling me it's probably a seized rear handbrake shoe or one of the springs has snapped?
Any pointers before I take the wheel off to inspect?