UPDATE - Well thanks for the advice all of which was carefully considered.
In the event, finding containers, syphoning off 70 litres of diesel, in a condo car park didn't appeal to me. I had to charge battery, charged it all day, left it off the charger overnight, tested again and it had held most of the charge. Connected it up. Checked for obvious signs of vermin habitation, couldn't find any, possibly because it is condo parking, walled all around and people come and go all the time. Turned on the ignition and left for a minute before trying to start. Fired up first turn. I did observ