Ok. lets look at the existing installation. At one time there was a single socket, on the RFC. Some time later, a double socket was installed along the wall a bit. This could have been a valid spur off the RFC, yes?
At the same time, or at a later time, the single socket was taken off and a blank plate was put in its place, the joint which made up the spur was then made from 30A connector behind the plate.
Here I come along and connect a SFCU to the conductors. At the moment it is no different to the spur off the back of the previous single socket.
I then run another cable from the LOAD side of the SFCU to 1 x double socket. This double socket, which is solely for TV equipment, is switched and fused.
The original RFC is in 2.5 singles. Original spur in 2.5 T&E. My new cable is 1.5mm T&E
I do not see this as a spur-from-a-spur