Having had another look, I do think Jim's right here. Those wires to the switch are singles. I was seeing what I expected to see. D'oh!

So the pickup wiring to the switch is probably 'right', but certainly needs to be tidied up as there shouldn't be those lengths of bare wire around.

Calum, can we have confirmation that the pickups have two single core wires from each pickup (one red and black pair, the other a brown and black pair)? I just haven't seen two singles being used on kit pickups, even though that's how Fender would do them.