Evening lads, I have checked with the customer about how the walls were treated, he cant recall other than to say non have been plastered to keep the costs down, all have been drylined and painted only, drylining only means that they put tape on the joints and smoothed them over he recalls... The builders only used 9mm plaster board on the walls, so when the orignal tiles were pulled off by another chap, the wall came with it, I've had to rebuild two walls the other two still have the paint on, I've put some Gaffa tape on it for half an hour and when I peeled it off the paint stayed on the wall is this a true indicator which can safely be used.. Just want to say a big thanks to all for your help...