When preparing for my driving test, one of the things I was told was that if you drove at 30mph in a 40 zone, you would be marked down. Do that consistently, and you would be failed for it. Because one of the requirements of being a competent driver was that you had to keep the traffic moving, which meant moving at a speed suitable to the road conditions.
Which, really, is as it should be.
As I was driving to work, I noted a number of vehicles with various stickers on the back, indicating that the vehicle was somehow limited in speed. You've no doubt seen them - they are becoming more and more prevalent on our roads.
Now, in many cases, these stickers merely note the (theoretical) limits applied to the vehicle by law - on particular roads, large vehicles have a lower speed limit that they must follow, and that's that. (I say theoretical, because it's a rule, not a true limitation - if the driver chose to break the law, the vehicle would indeed go faster. Not that I'm at all suggesting that they do, or would...)
However, I also noticed a few vehicles that weren't bound by law to follow any special speed limit, and yet had such a sticker. And, indeed, at least one of these was marked by a sticker indicating that the vehicle was limited to 68mph. This was on the M9, a road that has a 70mph limit along most of its length (although we were in a lower, variable, limit zone when I saw the van in question).
Now, I know that there's no legal requirement that you must drive at the speed limit, nor indeed is there a (relevant) minimum speed limit on the motorways. However, it is a condition of the driving test that you drive at an appropriate speed, and that you don't unduly slow the flow of traffic.
On a motorway with a speed limit of 70mph, very often the appropriate speed to drive is indeed 70mph. And a vehicle driving at less than that speed, especially one driving just under that speed, does indeed impede the flow of traffic - due to their presence, anyone who wants to go faster (most road-users) now have to move across into the single, faster, lane, slowly pass this one vehicle, and then proceed. The effect of this, especially a peak times, can be very significant.
In which case, I have to ask: why is it legal for vehicles to be limited in this way, when it is known that such limits will have a deleterious effect on the flow of traffic for everyone else?
#47: "Mockingjay", by Suzanne Collins (Not a comfortable read, even after the grimness of the first two. Still, an outstanding trilogy.)