On Sunday, 1 July 2018 10:37:28 UTC+1, ARW wrote:
"Fully flexible, 15-way high integrity RCD consumer unit supplied with
10 x Appleby 1G 35mm metal back boxes."

It might just be a genuine offer. Occasionally they or TLC do deals of free sockets or back boxes with a CU.

Anyway, if you want it, order it! And do a screen dump so when it arrives sans boxes you can complain.

Owain