BigWallop wrote:

SNIP


And the shower fitting has "fixed" compression joints to connect to the pipe
tails? And you checked that the fittings on the shower don't have any sort
of adjustment on them?

I take it the shower fitting is some sort of thermostatic valve that fits
between these pipes, and that the valve doesn't have elbow fittings that
will allow you to pull them out, or push them in, to suit a small amount of
difference in the width of the pipe tails. So, would it be possible to
replace the fittings on the shower valve itself, instead of having to make
the changes to the pipework?


The shower bar does not have compression joint but, not sure of the
name, the same type that fit onto taps, flat with washer. Again the
fitting is at the house, but I am 99% certain that there is not
adjustment, however I will have a look after Christmas when I am next
there.

Thanks everyone for your help, and a Merry Christmas and happy New Year
to everyone.