Problem solved. The first one I took off (downstairs) was full of water!! The (upstairs) shower is obviously leaking. Having dried everything out and put it all back, things are now working again.
Finally, Andrew 2022, yes, everything IS earthed!!
Thank you everyone for your help. I now need to head for the plumbing forum!!
Finally, Andrew 2022, yes, everything IS earthed!!
Thank you everyone for your help. I now need to head for the plumbing forum!!