There was some thing years back where they were supposed to be raising the limit in the far right lane of a motorway to 80, never came to fruition though.
I think 70 is perfectly fast enough. And around where I live, I would like to see it lowered from 30 to 20.
I also think that there needs to be a review of a lot of national speed limit roads in the countryside. 60 is far too fast to be racing around tight country lanes full of blind corners, barely wide enough for one car, let alone two, or god forbid, a tractor.
Maybe you'd prefer to live in the Isle of Man. A lot of roads there unrestricted.
But since from your post you seem frustrated and probably hell bent on speeding anyway, here's the official guide to speed limits, at what point you'll be actually charged with speeding and get a fixed penalty notice, and at what point you'll be taken to court:
Speed Limit | Charging Threshold | Court Summons Threshold
20 | 24 | 35
30 | 35 | 50
40 | 46 | 66
50 | 57 | 76
60 | 68 | 86
70 | 79 | 96
However, these are guidelines, so a police officer has discretion to act outside of them providing he acts fairly, consistently and proportionately.