Just noticed the the Lane Assist icon now only works intermittently.  Not that I’m complaining, as I’m not really a great fan of it.  I’ve checked that nothing is obscuring the camera so maybe it’s a change in the weather that’s confusing it.  As I said, it doesn’t really bother me but I have a slight concern that other gremlins are working away elsewhere.  The car is just over years old and I’m very pleased with it’s reliability.

Only works above 38mph I think 

You were right.  I didn’t realise that the Lane assist only kicked in at that speed.  Thanks for the advice.