Just off the phone to the elec specialist at the dealership
Told him what I had tested working with JTQ, and the last part when I mentioned there was no Voltage with the (-) and positive wire sitting out, he immediately said that’s definitely not right, and said it seems like a faulty panel.
He also mentioned that Swift fit 2 different panels, one which is light and flexible but sits slap bang on the roof, or another which is raised. He said the one slap bang can bring faults as the area it sits in can accumulate with water and with the frost every year faults can happen etc. He much prefers the raised for obvious reasons. He checked my VIN and confirmed I have the light/flex type.
He’s off now to speak to the service dept. and will book this in for a warranty repair. So I’ll fit the battery back (ensuring everything is off), if it’s flat by the time the caravan is with them, they will deal with it.