It won't be that.
All the brakes would drag and get progressively worse until that meagre 383 could not move the car.
You have got a dodgy Wheel cylinder or weak pull off spring or something else mechanical / out of round / incorrectly assembled on that particular wheel........
I will strip it out tommorrow and have a look Dave. I know Miles checked his adjustment so it must be adjustable. Makes more sense that its the problem on mine as both rears are getting hot rather than just the one on Miles' car...
Sorry Pete...missed your reply...ive got new cylinders, pipes, flexihose, shoes etc. Im scratching my head now to be honest. My rears have really needed to be adjusted up since I had the car so now ive put new stuff on it maybe it was badly adjusted for years to compensate for whatever the issue is. Its only come to light now I have adjusted them up properly???
Sorted....pushrod adjustment......shimmed the master cylinder with washers till sorted then adjusted rod down by thicknes of washers and no more heat....thanks Latil and co!!