My brothers a police officer. Back when he was on traffic duty he used to stop people like this (as well as the more usual dangerous drivers of course), because it IS dangerous not to make proper progress, it causes traffic jams and frustration in other drivers which can lead to poor decisions (yes that's on them too but it certainly should be avoided where possible).
He said most of the ones that drove like this shouldn't have been on the roads as they were often:
drunks trying to avoid getting pulled (including people who were regularly drinking the night before and then driving to work next day, I think op's driver might fall into this category)
Banned or unlicensed drivers trying to avoid getting pulled
people who's eyesight was too poor for driving but who were too stubborn/vain to wear glasses, in many cases wouldn't even go to opticians!
Elderly people who's confidence for driving really was gone and their reactions not quick enough either. Not saying ALL elderly shouldn't drive but many drive past the point they're safe to. It's often quoted on such threads "the most dangerous drivers are the youngsters" BUT the SECOND most dangerous age group is 80-85.
They REALLY don't belong on the roads.
One road he used to monitor was a country, windy road and it was notorious for accidents. Mainly caused by too slow drivers getting hit by other drivers going into back of them who were driving at a faster but not too fast for the conditions speed, hitting them as there was a sort of double bend bit so normal driver would round the first bend no problem and could reasonably expect that there wouldn't be another car round the second bend going so slowly as to effectively be an obstruction. Not sure I've explained that well hope you guys understand.
Anyway, of course the default is its always the car behind that's at fault right? Well the local courts started to get a lot of those drivers basically saying "fine I accept SOME culpability but the driver going too slow should too!" So the drivers going too slow got penalties too for I think about a year? Then the local drivers generally wised up and stopped driving dangerously slowly.
And the people in the second cars are only going around 40 max, the slow drivers have been as slow as 15mph on occasion (that one was on the local news as a "funny story" yet they were lucky the accident caused wasn't more serious).
What I do find amusing is that both extremes of fast/nippy and slow/hesitant drivers are the least efficient ways of driving so they're costing themselves a fortune!
"they also brake at everything meaning you have to be on high alert." Again, bro says this is usually because they're already banned or got points and paranoid about getting pulled for running a stop sign etc he says even now he reckons he's got a knack for spotting drivers with enough points on their licence that even a minor infraction will lead to them losing it.
You could call 101 with his reg no op, wouldn't surprise me if he already had points or was even banned already. Mention that you've noticed other drivers getting frustrated and as a result attempting less than safe overtaking and you feel it's a case of an accident waiting to happen. If he has got points I believe the police then can have a chat with him and if he's banned they'll be doing more than that! Are you able to give a fair description of the driver too? Just as if he's banned he'll likely try and say it wasn't him driving.
"YANBU, this is one of mine and DH’s absolute pet hates! I always say I think there should be a TV campaign to explain what the NSL sign means." I think the dangers of driving too slow/hesitantly should be advertised too.
"Can anybody tell me how it makes me a bad driver if I go out in my car tomorrow and choose to drive at 35-40mph on a 60 road, just because I'm enjoying the scenery and in no hurry?" As well as the other points made?its also
costing you money
bad for the environment (you're using more fuel and higher emissions)
creating traffic buildup (infrastructure is designed based on normal usage, roads are maintained and operated based on how many vehicles travel along them within a set time period. Which leads to greater wear and tear on the roads physically, plus the additional financial and environmental costs you're incurring to others and to make others do...
You want more?
"But my earlier point was that for people who are just on their way to work..." Most people need to be at their jobs at a specific time or they could well be disciplined or even lose their jobs. You could also be making someone late for a medical or other important appointment which could cause problems for them.
How about you give us a GOOD reason for driving far more slowly than is appropriate for the road & conditions?! The reason absolutely IS relevant because if you're not driving at a reasonable way for the conditions you're breaking the law.
"Perhaps he's conserving petrol/diesel" this is not the way to do that.
"So? What's dangerous about that?" You're not responding appropriately to changing conditions. PLUS it adds to congestion which increases likelihood of accidents. In extreme cases such congestion can lead to dangerous conditions for cars going the backed up road from others.
"but also contrary to the standards that your are expected to observe when taking a driving test." Most of the rules are there for safety reasons too.
"The reason it's dangerous is to do with the unexpectedness of coming upon a vehicle at a considerably lower speed than the road speed limit and conditions indicate are appropriate, for other road users who are driving to a sensible speed, making progress. To suddenly come round a bend (same on a motorway even) and come up against a vehicle going at just 30 mph is an actual physical danger that could cause an immediate crash - that's a bit more than an inconvenience and a cause of frustration!" Puts what I was trying to explain much better!