On 04/05/2020 21:01:38, GB wrote:
I have found these right angle brackets to mount an exposed shower mixer
- the type like a long bar.


https://www.victorianplumbing.co.uk/...for-bar-valves



Does anyone know whether I can get one that is a single bracket with
both parts mounted on it?


Like these?

https://www.ebay.co.uk/itm/THERMOSTA...S/173181946791

I have used the type you've linked, but pretty sure they were full
circle type and were fed from above. Sometimes there isn't the luxury of
access either in or through the wall.