Well I'm hopeful about my battery. I've had it on a repair cycle and charge cycle for a couple of days and there are signs of life. I needed to turn my caravan around on the driveway so gave it a try - a couple of minutes at most and on a gravel surface. It coped very well and only dropped half a volt or so when finished. Its now back on charge again and I may put it through a repair cycle again.
If you interested about lead acid battteries and repairing them, there's some interesting stuff here.
I'm hoping Santa may bring me a Ctek charger but for now I'm using a cheapo one like this. It appears under a variety of names and obviously comes from a state owned factory in the Middle Kingdom.