MilRob

Thank you all for your helpful advice.

We have a friendly Subaru garage, 3 mins walk away, who did a quick check and tracked the problem to the column switch; and you guys pointed me to a s/h tested replacement from https://www.mgfntfbitz.co.uk/ for £24, plus your simple refitting instructions, so I will get them to do this. Phew!
Thanks again.