Gordon Henderson coughed up some electrons that declared:

Thanks for the links - good reference though. I'll pull the dishwasher
out tomorow (Which the pipe runs along the side of) and get a better
look at it and see if there is any identifying marks and I'll be better
able to size it then too.

Gordon

On an aside -

I found these clips (so called hospital clips) to be very good for mounting
the stopcock. They give an exceedingly solid mount and tight clamp to
copper pipe:

http://www.bes.co.uk/products/159.asp

Item 6504


When I ran my new bit of MDPE into the house, however I rotate and tighten
the fittings it always seems to develop a bit of torsional stress and these
clips hold it solid.

Cheers

Tim