Just had to look it up, vary interesting.The ring system , and fused plugs, means you don't need individual circuits for each socket, and because each ring is fed via two pieces of 2.5mm cable it's effectively 5.0mm wiring - yet uses much less cable (and copper) than radial wiring.
https://en.wikipedia.org/wiki/Ring_circuit
But as they point out it has a dangerous fault mode.
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