I also started looking at the front indicators as the wiring inside the wheel arches looked wrong - too many wires - I took the headlights out & found this. The LED headlight units have built in LED indicators so there was a relay to turn off the side lights when the indicators were on, but the old LED indicators were still in the bowls as well as the original indicators still being in the bodywork below the headlights.
There were a few horrors, the power for the indicators had been taken by stripping the insulation from the feed wire, wrapping another wire round it by a couple of turns, then wrapping the whole in insulating tape. No solder, no connectors, in a wheelarch where it's all going to get wet.
^^This is the wiring that came out of just the headlight bowls.