Got the electrics sorted
In the end, today I removed every connector from the fuse box that I could and removed all the relays.
Decided to start with the emergency flasher as this is powered even when the ignition is off. Connect the main cable from the battery to the fuse box. Insert all the relays then disconnect the earth that jumps from the flasher to the other switches (wipers and lights). Connected the cables from the flasher to the fusebox and………….. Same shit - drop in voltage and the relay going bananas.
Checked the fuse box and noticed that connected to the same connector as the main battery cable was a cable to the lights relay so unplugged this……. The flasher worked!
Put the cable back that I had just removed and the flasher still worked….!!!
Slowly started to add each switch in turn and constantly checked until everything was connected.
Only thing that didn’t work but was an easy fix was when the sidelight/headlights were on, the offside rear light wasn’t on - remembered that one of the cables for this had lost its fitting and was loosely connected so went in the engine compartment and touched it properly and the light came on so need to get a connector for it and solder on.
Didn’t test the brake or reverse lights yet. Will need a partner in crime to test the brake lights.
So - all good. Phew.
On to the next phase