The hose goes from the central mixing block, which is made from brass and diverts the flow between the shower monsoon head, the shower spray and the water jets, so this hose is just one of three, the hot & cold water also connect to the block via tap connector braided hose. I looked everywhere for the part to no avail, the closest I got to it was a marine fitting website, anyway I did sort it in the end, the pipe accepts 15mm sleeve inserts, so I simply placed a female reducing elbow with a 15mm compression joint on the tube, plenty of PTFE and the jobs seems OK. The fittings on this cubicle really are cheap, in time I would like to replace them all with brass, the proof will be in the pudding and the shower goes into full time operation today, with three teenage kids in the house it should be fully commissioned by the weeks end.
Thanks for all the advice guys.
Regards Otto