After serious thinking Mathew Newton wrote :
Measuring the L-L and N-N resistance on a ring circuit is giving me 0.7 and
1.1 ohms respectively. Does this point towards a poor/loose neutral
connection in the back of a socket somewhere? If so, is there a good way to
locate where through testing as opposed to removing each socket for direct
inspection?

Visually check each socket's face, for signs of any over heating.

With the power off, you could make up a pair of (naughty) plugs with
bare wires coming out, then work your way around the ring, comparing L
to L and N to N resistances across sockets in the ring, until you
localise it, then delve into the socket for the cause.

Measuring such low resistances has always been a tricky problem.