Major clutch issues, anyone seen this before?

[Steve4012]

I thought I'd round this problem off now I'm confident I have it solved after quite a few hundred miles. It turned out to be three issues. Firstly the pressure plate and bearing weren't correctly sized, as most of the replies suggested. Steve at SJ finally acknowledged this, not verbally, simply by exchanging the clutch pressure plate and bearing for the newer versions and refunding the 2nd bearing I'd bought after the first one was broken when the clutch seized. Mistakes happen and it ended being resolved ok so I have no problem with Steve. The second issue was the clutch slave cylinder. Although only a couple of years old there was a weep inside the rubber cap which was impossible to see. This released a small amount of pressure and allowed the clutch fork to just hang there. Sometimes when the clutch was pressed the fork would realign itself and centre the bearing, sometimes it wouldn't  resulting in an off centre contact to the pressure plate and clutch judder. Match this issue with the wrong size bearing outer and spline inner and disaster! The third issue, a small one, was the squeak. Because there was so much lateral play on the fork and bearing, the last time I re-installed the gearbox I was paranoid about having put too much grease and causing sliding of fork to bearing so I skimped on the grease. Obviously too much and the lack of lube caused a squeak between clutch fork and release bearing collar. Thankfully this was resolved by managing to get a few drops of thick oil down a tube inserted into the clutch fork hole into the right area and the squeak was gone. 

Thanks to all that gave input on this thread, it's much appreciated and with these strange times the car is currently my daily driver!