The maximum motorway speed limit in the UK is set at an unrealistically low level, given the advances in technology of modern vehicles in respect of speed and safety.
The limit should ideally be removed altogether as in Germany but, if that is too much of a step to take in one go, at least it should be increased to 85 MPH, which would approximate with that which applies in France.
It goes without saying that a) vehicles should be driven at a speed which takes account of the prevailing conditions, which may mean that it is appropriate to drive at a lower speed than the limit, just as at present, and b) motorway sections which are regularly congested may be subject to lower temporary or permanent limits, as at present.
Why does this idea matter?
Current limits lack credibility. They are frequently ignored and modern cars are capable of cruising safely at speeds well in excess of them. Speeding is not a factor in more than a small minority of accidents.
Before the 'road safety' lobby become too enraged, it is not unreasonable to expect that a driver concentrating closely driving at a speed at which s/he feels comfortable is likley to be be driving with considerably more care and attention than one who is driving along at a lower speed than s/he really feels is appropriate and whose mind is more likely to wander. This particularly applies motorway driving, where monotony and a lack of changing circumstances can result in there being little in the way of external stimuli to maintain concentration.