Thanks again to all who've dipped into this thread. This is where I'm at now:
Took the battery out of the car last night and left it charging on our newly acquired 6A charger. This morning the charger LED (doesn't have meter) shows "Fully Charged". However the small round indicator on the battery itself doesn't show anything - or it's dark/black. I'm not sure how reliable those on-battery indicators are but the key alongside it states "Green" for sufficiently charged, "black" for insufficiently charged and "yellow" for replace battery.
Also it's not clear what make the current battery is. It's labelled "BMW" but doesn't have any BMW or Mini logo so I guess "BMW" in this sense just means "suitable for". There's no other brand on the battery. Photo attached
Putting a volt-meter across the battery does seem to show around 14vdc at the moment so I guess the next step is to put it back in the car and follow the diagnostic steps from
- unless people think that the on-battery indicator showing nothing / insufficiently charged is a good reason to invest in a new battery ahead of winter anyway?