What would be a convincing arguement?

Via Devils Kitchen, the government are to reduce the national speed limit.

Jim Fitzpatrick, the roads minister, defended the plan, which will be the most dramatic cut since 1978, when the national speed limit was reduced from 70mph to 60mph.

“There will be some in the driving lobby who think this is a further attack and a restriction on people’s freedom,” he said. “But when you compare that to the fact we are killing 3,000 people a year on our roads, it would be irresponsible not to do something about it. I’m sure that the vast majority of motorists would support the proposals.”

Hmph, here's Jim Fitzpatrick saying we have fewer than 3000 road death per year

Road Safety Minister Jim Fitzpatrick welcomed the decline but said road safety improvements were still needed.

"These figures are extremely encouraging. They show that for the first time since records began in 1926 the number of people killed on our roads has fallen below 3,000.

Whilst that was in the middle of last year, its possible that road deaths have crept up by now.
Hmph, here's the Department of Transport in January this year saying road deaths are down fifteen percent in third quarter 2008

The provisional estimates show the number of fatalities in road accidents were down by 15 per cent for the twelve months ending September 2008 compared with the previous 12 months. Total casualties were down by 8 per cent, and killed and seriously injured casualties 8 per cent, compared with the previous 12 months.

So the most recent stats on road deaths have it at about 2,500, the lowest since records began in 1926 (again).
Bah, back in the old BBC article Uncle Jim goes on to say:-

"But these figures make us determined to do even more. Far too many people are still dying and we will continue to do everything we can to improve road safety and further reduce the numbers of people killed or injured."

If a reduction in road deaths makes the government determined to do more, what would make the government determined to do less? Like what kind of evidence would be required for the government to raise speed limits and remove speed cameras?

I can understand if road deaths were rising then the government should be determined to do more, but that's not the case.

There has to be some logic here, something that would persuade.

What can the UK do to be permitted to drive faster on the UK's roads?