The earth wire goes to the shade in the 3-core - makes rewiring and reassembly even more fiddly. Fortunately there's a 30mA trip on the sockets, as one would expect; the lighting circuit is on 100mA, The 3-core braided flex looks good but it's rather expensive. The headline price is £1.49 but selecting 10m (2 lamps, possibly) shows £24.99! I had a look for some flat 3-core sheathed flex, with no luck. Searching isn't made easy due to so many sellers using 'flex' for cable - and one used it for SWA!