Just took the car for another test drive - airon off. At low revs (eg, reversing), the battery light comes back on and steering gets stiffer.

Hopefully this points more towards a loose belt? I'll run it to the dealer tomorrow to see what they think. If they need to tighten the tensoners would an hour of labour be about right?

Hope I'm right - this
will be expensive enough

And the Summer 168s were just about to go on in honour of spring finally coming !!!!