I have never been one for plumbing. Never has worked for me. Having cut off some of the pipes a week or so ago I needed to cap a few ends. I bought 3 different size caps and none fitted. So this weekend I took off one of the screw fittings and a bit of pipe. I have now tried 2 places. Nothing is the same size!
The pipe looks to be about the same size as 15mm (the new standard) but it is ever so slightly bigger (enough that 15mm fittings will not fit). The wall thickness of the pipe is also a lot thicker than modern pipes and I think this is the main issue. But not the only issue. The screw thread on the thingy on the pipe does not fit any metric or imperial measure other thingys!
What this means is that none of the cold water piping is usable (or will need some form of soldering). I have spoken to a few people who said not to muck around and just get rid of it or it will drive you mad for ever more. This is good advice if it was not for the fact that all the cold water pipes (the near 15mm size) comes from some really big (and no doubt equally non standard piping) which is not easily replaced.