Yes it is BC.
I decided to put the controller in the garage for a trial run before I go chopping the hallway around.
I chopped in a back box for the switched fuse spur and a surface box for the controller , I surface mounted the controller in case I do move it at a leter date.
The latter turned out to be an error as they are ( realised once I done it all of course and was on the final leg of the day ) only meant for use with back boxes. In the end I used a cut off of electrical connector ( brass removed ) as a spacer between the screw holes and the backing plate of the controller.
If anybody tries this in the future I'd say the front of the wired backing plate needs to be 1mm back past flush with the box.
Anyway , finally just finished and the floor is now getting toasty.
Cheers
Diggy