"It's a bit hard to follow the two-chevron rule"

No problem, if you're driving sensibly anyway. Which reminds me. I was driving back from Widnes a few Sundays ago, and it was a bit foggy. The visibilty crossing the Mersey was down to a few hundred yards each way. Then I joined the M56 at Frodsham and the visibilty dropped, so that slowing to less than 60, I knew I was far enough behind the vehicle in front if I could just see the lights through the fog. The worrying thing of course was all the cars, mainly grey, flying past with no lights! Talking about being in a hurry to get to your own funeral!