I actually think these numbers prove nothing for either side of the argument. The debate is regarding a rise in speed on motorways, so unless you have numbers of people killed on motorways due to driving faster than 70, they prove nothing.
I found this enlightening;
How many people are killed or injured on Britain’s roads?
Great Britain has one of the best road safety records in Europe and the world. Despite massive increases in traffic over the last few decades, the number of people killed on our roads has fallen from around 5,500 per year in the mid 1980s to under 2,000 in 2010. However, this still means that around five people die on Britain’s roads every day.
Reported Road Casualties in Great Britain, 2010
Killed - 1,857
Seriously Injured - 22,660
Slightly Injured - 184,138
All - 208,655
These figures are for road accidents in which someone was injured on a public road and which were reported to the police. Although virtually all fatal road accidents are reported to the police, it is known that many involving injury are not reported, even when some of those involved required medical or hospital treatment. It is estimated that the total number of road casualties in Great Britain is between 680,000 and 920,000 per year, with a best estimate of around 800,000. This includes an estimated 80,000 people who are seriously injured.
Common causes of these unnecessary tragedies include:
Speeding
Around 600 people a year are killed in crashes in which someone exceeds the speed limit or drives too fast for the conditions.
Drink Driving
Around 400 people die a year in crashes in which someone was over the legal drink drive limit.
Seat Belt Wearing
Around 300 lives each year could be saved if everyone always wore their seat belt.
Careless Driving
More than 400 deaths a year involve someone being "careless, reckless or in a hurry", and a further 200 involve "aggressive driving".
At-work
Around one third of fatal and serious road crashes involve someone who was at work.
Inexperience
More than 300 newly-qualified drivers and their passengers are killed in car crashes a year.
From here;
We could say that actually only around 600 could even be atrubuted loosley with speed at all?