Clutch slave pipe quick release - how does it work?
 

Can anyone advise please - I don't want to damage anything. I thought that pushing the grey, diagonally split collar forwards, into the big gold part, would release the coupling, but doing this does not seem to work.

Sorry can't post a pic.

OK, found a pic and description in Haynes, showing the plastic collar (dirty, not grey!) being pulled rearwards, and with slight leverage from a small screwdriver, the coupling parts separate. As far as I can tell, it is supposed to work like a hoselock, or plastic plumbing push-fit connector. The collar moves easily to the rear, evenly and all round, as far as the larger diameter part of the gold main pipe ferrule. Attempting to lever the connector apart has split the collar, but with no movement in the connector. Are these usually as stiff as this, or am I still not getting this right? If I wreck this connector, I will have to replace the pipe all the way back to the master cylinder or alternatively, find a way of making a conventional connection, and bleeding the clutch. Help!!

Thanks to MG John's post on this topic, and the advice from others that the plastic collar has to move fully forwards, I successfully employed the slim 17mm spanner method to separate the joint. These cars may at times be frustrating, but there's always someone who has been there before you and found a solution. This is the advantage of a proper forum, real enthusiasts, real knowledge, not the argumentative and fake stuff you tend to get so much of on Fakebook!:}