Thanks everyone. Interesting links and much reading material (phew) but now I actually feel quite depressed at the thought that no amount of evidence is ever going to be enough for this government.
When it comes to regulating speed though, if you allow the general public to decide what is a safe speed you are bound to get into a situation where drivers who
are going too fast for the conditions will argue it
was safe and the police saying no it wasn't.
You cannot have a situation where every case of excessive speed is argued over, otherwise the policing would be compromised. The thing about speed limits is that there is no argument, from the laws point of view, and that makes it simpler to enforce than the much more nebulous idea of what was 'safe for the conditions'. (just playing devils advocate here for a moment)
Enforcing what is safe is neigh-on impossible because each person will have his or her own opinion. Without enforceable speed limits, what else would the police have to work with? No amount of bobbies in cars will ever be enough to make the vigilant road bandit drive sensibly just as no amount of training will make them drive sensibly for the conditions.
That said, I believe even the nutters out there
would drive more carefully if they were made to see the results of accidents, like I have to in my work (amongst other sad things). You can't become a good chef without seeing a few broken eggs, although I admit making them go to the morgue may be going a bit too far