Just wanted to check that I was reading the OSG correctly!

If I use Reference method A (i.e. enclosed in conduit in insulated wall)
then 2.5mm flat T+E cable will be sufficient for a ring circuit.

Presumably I cannot put 2 cables in the conduit (i.e. to and from the
socket) as this will derate the circuit under 20A and I would need to
increase the size of the cable.

The alternative is to ensure that the cable is touching the inner
surface of the plasterboard and that the two cables do not run in close
proximity to each other.

Cheers

Martin
--
Martin Carroll