I voted to leave it as it is. The speed limit is there to protect you should somebody else have an accident which then smashes into you. On a single carriageway road, if somebody coming the other way loses control and veers towards you the collision speed is 2*60=120mph, not something I want to see increased.
And really, how far are you travelling on the motorway that you're going to get somewhere significantly quicker travelling at 80mph rather than 70mph? It's a matter of ~10 minutes per 100 miles travelled.
In my opinion, what is needed is enforcement of all the rules of the road not just the speed limits. If we can crack down on all the inconsiderate people who put other people at risk then we can all get on with the job at hand, getting from A to B as smoothly and safely as possible.