A ghost in my brakes!!!

My 02 S80D5 has started a non sensical issue with the rear nearside brake. I was at a concert in Belfast last night and I had to collect my father enroute. I stopped at his house and could smell a strong burning smell, we discovered n/s rear. Pushed for time we set for Belfast, a 70 mile journey. On arrival to Belfast I checked wheel and it was as the rest. Wheel cold to touch and disc only warm, same as other 3. On the return journey approx half way the car started to vibrate, I pulled over and discovered the disc was red and glowing in the dark. I waited for it to cool and set back for home driving more cautiously. I stopped about 20 miles and again at home and both times everything was normal. Then tonight, driving all day without issue then took my partner to the shop and as she opened the door I got the smell and again the lot was roasting. Automatically I'd assume a seized caliper or stick pad or something along those lines. Unfortunately this situation is not that simple as I can move the car at any point even when its roasting with one hand. There is no resistance and no noise, in my experience a seized caliper or sticky brake would cause both a sound and resistance especially when only being pushed with one hand. O' yeah and p.s. rear discs and pads are new!!! I didnt chsnge handbrake shoes as they were fine.

It could be that even though the handbrake shoes looked fine, they delaminated, and are sometimes rubbing against the disc whilst you're driving.

Off with the discs again then :shockedbi. A major pain in tbe backside !!

I had a similar issue few weeks ago, turned out it was actually the handbrake shoes delaminated

Had everything off again last night. Handbrake shoes good. Handbrake on, holding. Handbrake off, turning freely by hand with no rubbing. Brakes on, calliper clasping on disc. Brakes off, calliper releasing and brakes turning freely without rubbing. Sounds good!!! Not so, drove the short 10 mile journey from my fathers house home and before I got home I had to pull over. Vibrating from car and when I stopped the disc was glowing red!!!