Interesting. Maybe I should have pointed out that I live in Scotland. Up here, most people do actually drive to the speed limits on motorways / dual carriageways, in other words on my daily commute on the M8, there are three lanes. Inside lane doing around 60, middle lane 65-70, outer lane maybe 80, but usually just overtaking. We holiday in England, so I have experience of driving down there (A1 / M1, M6 etc) and I would say that you would struggle to do less than the speed limit there - though I find the A1 / M1 to be nuts and not very safe at all. Everyone foot down, lots of lane changing, lots of last minute braking.
I guess I just find the mini more comfortable and enjoyable when cruising a little slower. My normal daily (old 306 td) I drive at the limit or slightly above everywhere.
Agreed that too slow is dangerous, but I would dispute that if I was to head out onto the motorway in my mini and blast up it at 85mph - thus hassling the majority of drivers in the fast lane to get out my way and change lane - that this would be safer than sitting in the inside lane doing the same speed as everyone else and not requiring to change lane.