The Appendix 15 argument.
Appending 15 is informative only, it doesn't matter how many times people claim it is a regulation, it isn't, it's there in black and white (INFORMATIVE).
All the appendixes are informative with the exception of the appendix 1.
The opening text reads "This appendix sets out options for the design of ring and radial final circuits for household and similar premises in accordance with Regulation 433.1"
It sets out the ‘options’ by indicating what can be done and what is acceptable.
Options... it is not the exhaustive list of possibilities that comply with 433.1, if it were some of what we do everyday would be non-compliant (like a 20A DP switch feeding a single socket for an appliance wired in 2.5/1.5mm cable - complies with 433.1.204 but isn't on the diagram in appendix 15).
Where does it say that it’s not exhaustive?
For a ring circuit to comply with the regulations, it must comply with 433.1.204 which defines the acceptable topology of a ring final circuit purely in terms of cable loading. Thus providing the cables are not overloaded in accordance with 433.1.204, a lollipop or ring final circuit will comply.