Just to close this in case anyone searches these symptoms in future - took car in to dealer today - small auxiliary battery in the boot had at some stage recently gone low on charge and apparently once they are low they will not come back to life despite smart charging.
Dealer fitted new aux battery and turned light off. Tech suggested smart trickle charging using under bonnet posts at least monthly if car not used (ie not charging this battery)
The lamp illuminated was in the pic.
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