| Okay, serviced now, the clutch slave cylinder had given up the ghost. It was replaced for £65. They cannot be rebuilt as its a sealed unit, as is the master cylinder which is £85 to replace apparantly.
According to Italsport in Bury, Lancs (highly recommended) its the first time that they had known one of the new type of sealed units let go. I almost felt pleased with myself !!
As Dave0749 says the sure fire sympton is hydraulic fluid visible when you loosen off the slave cylinder.
New belts installed and slave cylinder replaced for a reasonable £330 | 
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