I just measured a new clutch driven plate and it is indeed 7.9mms thick. If you need any other measurements while I have the clutch to hand just let me know
If they are only 7.9 from new, then I have plenty of meat left on mine.
I had just done my first oil change since buying the car, and found that you can't pour it in the top too fast, the hard way. BLUP and it belched oil up and over and down the back of the motor. Went under to clean up and decided to take off the tin bell housing cover while under there for a "look see".
I thought it looked thin but obviously not. Only a small motor after all !
Thanks Chris for your help.