In reply to Andrew Wilson:
ok, not quite - and I assume you'd guessed that, but just wanted to be pedantic about it. So let me be clear.
For a distance of around 6 miles, when appropriate, I would indicate to the driver behind that they hadn't dipped their lights.
I'm not after a critique of driving. And on this forum, no, I don't expect anyone to join me in anything. I've found this climbing forum to be the most toxic, unfriendly community I've ever joined.