The best i can do at the moment is send you the link:
http://cgi.ebay.co.uk/THERMOSTATIC-BATHROOM-CHROME-MIXER-SHOWER-VALVE-TAP-W87-/330341967665?cmd=ViewItem&pt=UK_Home_Garden_Bathroom_Shower_Units_PP&hash=item4ce9ea6731
Dont know if it helps?
Help, I have recently ordered a concealed arm shower fitting, but once assembled allows no space once fitted to place a tile behind. Is there any way of extending the thread??