The link below has statistics a bit out of date, as they are from 2011.
According to them:-
the M1 is the most dangerous Motorway in the country,
the A6 the most dangerous single digit trunk road,
the A38 the most dangerous two-digit trunk road,
and the North Circular (A406) as the most dangerous three-digit road.
(Dangerous=Deaths per mile of road per year)
The information seems all very concise, but where is the year-on-year data that will tell you trends, and stuff?
It worries me that with the rapid increase in traffic pushing out the duration of our rush hours ever further… There must be some finite point in the not-too-distant future when 24/7 becomes a “permanent” rush hour - at least on a statistical level. 
