With the future changes in vehicle control technology with a view to much improving road safety for all using UK roads, I am sure the better graduation in speed limits will go a long way ensure this implementation is a lasting success.
You may be interested in these active petitions
Statistics appear to show the greater number of road accidents causing serious injury or death are on country roads,not motorway or trunk roads. Speed appears to be a major cause of such incidents. In particular changes from 30 to 60 (and reverse) where accelerating and braking are frequent actions by the less sensitive drivers. Changing the 60 mph to 50 could then give a smooth transition in 10mph increments. 60mph should be reserved for a half mile section on leaving or joining a motorway