by this point as its been on charge for a couple of days and failed to charge above 7V, I concluded the battery installed is going to take much of a change no matter how you do it.Which ever jump leads you use, it’s worth waiting for 15-20 mins with them connected and the donor vehicle running to charge the dead battery.
To be fair, the connection of the neg jump lead is not really going to make a whole lot of different in your case as your battery is already screwed and your ECU is completely confused as to the state of charge, but yes the neg jump lead should not be on the battery.Ah no on the terminals, oops!
good news!All sorted now, thanks to all who commented