That's not really news, is it?
We've had "congestion speed limits" on the M25 and M42 (and probably other places) for some time.
Lowering the limit and keeping it flowing is fine, its the sensors and average speed cameras that annoy, you end up watching the speedo instead of the road.
They should spend some money improving the surfaces and filling potholes properly, instead of "new technology"
In reality its another Stealth Tax, all this green and speed kills stuff is crap, its industry that pollutes the most, not car drivers.
Lowering speed limits does not save lives either.
(I do appreciate that if you have lost a loved one, you may well have a different view, I would too)