Since you have no connectivity on any of the conductors, try to work out whether the circuit really is supposed to be a ring or whether it's just a radial branched at the origin. What's the conductor size, and the fuse or breaker rating?
Identify which sockets are served by that circuit by powering on one circuit at a time and checking what's live. No point testing sockets that are on another circuit.
Assuming two cables into one fuse or breaker, disconnect the circuit from the supply. At the origin, connect any two cores of one cable together, say line and CPC. Work outwards from the origin, measuring the resistance between the two selected conductors. Disconnect the cores and repeat for the other cable. Of course, you may have to inspect some of the socket wiring for evidence of spurs and perhaps disconnect some sections and test separately. This should give you a picture of what's connected to each cable and how far from the origin each socket (or other load point) is.
If you're satisfied that you know the layout of the circuit, re-connect the ends to form a ring and re-test to the regs or replace the fuse or circuit breaker with one suitable for the existing circuit arrangement.
Edit: I see, Richard, that we are thinking along the same lines.