Hello Zimmy,
From your later response you have what is called 'drag', not slip, the two are opposite in meaning.
As I said in my earlier post,
"If so the first check is for freeplay of the slave pushrod, about 1\8" or so, if you have none that is the problem."
I repeat, check the free play, it now sounds as if yours is excessive, and then adjust to achieve about 1\8" clearance. By the way it is essential that there is some free play. Also be sure that the slave cylinder is correctly positioned, i.e. not fitted on the wrong side of its mounting. (Not sure about your Midget but this is possible on some cars.)
Alec