Thanks for the great tip.
I got my discovery back last night after having the rear floor replaced, seeing as the seats and carpets were out I thought I might as well try this on my tatty headliner.
I took the liner out this morning, took off the cloth, rubbed it down and painted it with emulsion.
A you said, it don't half soak up that first coat but by the third coat it looked pretty good.
Gonna stick it back up tomorrow.
Once again, thanks.
Andy