Thanks, Pleiades. I've checked all PC connectors on the right hs of the bike and all connectors are so far made and clean. Just having a cuppa before taking the tank off to have a look under. Spark Plug is bone dry.
I'm still drawn towards an Immobiliser freeze fault and to this end I removed the Batt connections again and let the thing sit, keys out for a couple of hours, but no joy.
It's hard to believe taking the batt terminals off could lead to all this!