Update:
There have been some developments in the last few days on this - though I've still not got a fix!
Day 1 - Mate drove car and noticed the n/s rear brake disc was red hot (much hotter than the other side). Took car to garage that had previously suspected the clutch and after we pointed out the brake seeming to stick he said the cluch was fine and said the problem is with a seized calliper and cable. Replacement single calliper, brake cable and new pads £260.
Took to another garage and told them brake seems to be sticking - freed the mechanisms off and greased up and advised if it happens again it may need new callipers - £120 per side with pads.
Day 2 - Car seemed to be driving better after this (maybe placebo though) and somehow seemed less effort when driving with both brake discs staying equal temp. Soon went back to normal though so decided to book in for new callipers. Unable to book in for a few days I called the other branch of the same company and arranged to drop off for new callipers.
Day 3 - Dropped car in as arranged. Received call a couple of hours later to say they have found nothing wrong and there is no need for new callipers BUT the clutch is slipping a little. Problem is the same and now the handbrake points skyward when applied!
Now, I have tested the clutch every way I know how and so has my mate and neither of us can feel it slipping! So, as the disc is getting so hot on one side again this HAS to be a sticking calliper, right?
I always thought it advisable when changing brake pads / callipers to do both sides at the same time whereas the first garage seems to think this is not necessary and that we can just get away with a full set of pads. Seems a tad pricey at £260 though (single calliper, pads and brake cable).
What to do now?