my rover 75 cdt developed a spongy clutch pedal but still went into gear and drove fine. now cant get any gears wen car is running is this going to be the clutch or could it be slave/master cylinder or all 3

The master and slave can play up but more common is for the clutch arm to seize in the box. Get someone to work the clutch pedal and watch the arm to see how much movement you have

That happens on the PG1 box but not the 75 box I believe as they have a silly internal hydraulic slave cylinder.

Yep, it'll be either the master or slave cylinders, very common problem on the 75.

Master cylinder is the most common, as it's absolutely tiny and holds hardly any fluid, so even the smallest leak causes huge problems.

Pop the panel off under the steering wheel, stand on your head and shine a torch up at the top of the pedals, should be fairly obvious if it has a problem, it'll either look damp and shiny or just be empty. Not particularly expensive, but can be a bit awkward to replace unless you're good at yoga.

If it's the slave, then it's a gearbox off job, unfortunately.

Mine has this problem

If sat in moving traffic with the clutch depressed it eventually sticks down and you have to pull the pedal back up to get it out or into a gear

I was going to change Master,Slave Cylinder and the clutch while i have it down

My ZT has only done 42,000Miles but was bought with a towbar so not sure how much hassle it has had before me