Will -
When you bleed the system if the fluid has any black particles in it, then it is a sign that the rubbers have perished in the master cylinder which then needs replacing.
When my clutch failed up a Swiss mountain it was the slave cylinder which, as Rog says is an engine out job.
If you do have to take the engine out then upgrade the clutch plate as the stock Morgan one has poor quality springs that commonly fail.
Upgraded Clutch Plates are available from Phil Bleazey or M3W Services.
