mounting consumer unit

[Bright.Spark]

Just a quick one this time I promise. I've got a fuse board to mount tomorrow for my napit assesment, is there certain requirements I need to meet, eg does it need to be spaced off the wall and mounted on ply or is screwing it to a wall with no spacing acceptable?

 

[telectrix]

either is acceptable but, esp. if the wall is uneven, ply or contiboard behind. either way, the board behind the CU looks more professional.