Yes, I tried switching lamps around and the same two sockets work, whichever combo I go with. Makes me wonder if there are two separate loops!Could try putting the old lamps back in, see if the work.
If they do its a lamp issue, unlikely but woth a go.
If they don't then its wiring,
If theyre loop in loop out wired and none of the lights work the issue probably lies at the first fitting, loft unfortunately.
...or the loop out to the other lights is loose from one of the working lights.Yes, I tried switching lamps around and the same two sockets work, whichever combo I go with. Makes me wonder if there are two separate loops!
I see dodgy connector blocks and insulation tape.I'm 90 minutes drive from you, Thats 3 hours non productive van-sitting.... but there might be another member closer that could give you a hand.
Experience gives you a 6th sense when it comes to fault finding.
"I see dead people..... and loose connections"