Richy,they're definatley not in sync, the big question is why ? Why it runs perfectly disconnected is another wonder. I've been getting some guidance from another forum too and a guy who is in the trade and into electronics. His view is that when cranking over something is interfering with the ecu comms and or drawing excessive voltage, since it starts easily on a bump that may point towards the starter circuit. I've found that the alternator is only putting out 13.1v too. Its positive cable is linked via the starter so it could be an electrical fault/draw there. With the alternator disconnected from everything its still a no start which rules it out as drawing excessive power. I know the starter cables can fail/burn out on the Antara too again due to starter voltage issues.
There are 2 different starters for the Antara depending on stop/start or not. I don't know the technical differences between the 2 but I'd guess that fitting the wrong one may have consequences, perhaps thats been done on mine. I have one on order from Germany, 2 weeks delivery but £70 cheaper ! Cars parked up now until it arrives. Hopefully I'll be back in a couple of weeks with a positive outcome.