John Rumm wrote:
(For various reasons, he is keen to rewire with as little disruption as
possible and is happy to accept the limted numbers of sockets etc he
currently has

He might be, but IMHO it would be irresponsible to install a circuit
which would not be sufficient for the purpose by today's standards.

- so being able to reuse the conduit drops to the sockets
would be ideal, but they are only large enough for one cable, unless the
circuit is wired in singles and conduit added everywhere).

Would it be acceptable to go *down* one conduit to a socket,
horizontally along the wall (either chased or mini-trunking) with
intermediate sockets, to socket at another conduit and then back *up*?

If minitrunking, a bit of slack would offer the possibility of chasing
in at a later date. Horizontally between accessories is a permitted zone.

An alternative is to use radials, not rings. Then any additional sockets
required can be spurred off existing socket locations, without having to
do down-along-up to preserve continuity of a ring.

Another thought is MICC cable might be thin enough to get 2x down a
conduit. IIRC rings only need 1.5mm minimum in MICC, not 2.5mm? Would
involve some faffing and making good at the socket locations though to
accommodate the glands.

Owain