Phew.
Well, nothing accelerated overnight and I’ve now moved the kitchen unit it was behind.
It does look as though its leaking at the gland so it should be easy to fix although the stopcock looks very old.
I hope its not worse / doesn’t get worse while attempting to unscrew it – whoever installed the kitchen prior to us living here plastered over the top/bottom joints so if they are leaking some bashing will be required. As we are having a builder in prior to a new kitchen install in March I think I’ll be getting that sorted at the same time with a new stopcock added.