I'm another that uses cruise at 62 in the mornings, A27, A23, M23. The reason I do this is because the amount of idiots sitting in the outside lane tailgating each other to do 70+ is beyond belief. The inside lane can be completely empty but they will all still sit in the outside lane less than a metre off each others bumpers. Amazing amount of these vehicles are large vans or small cars, its hardly ever a decent motor.
For a journey that I do twice a day, every day its simply too stressful to try and press on doing 70ish. At 62 I'm back peddling along lane 1 and occasionally have to swing out for a lorry or very slow moving car.
When you use cruise control it opens your eyes as to how erratic peoples speed is and generally they do speed up when you over or undertake them.
Last week I was in the outside lane on the way home, doing the limit as I wanted to get home (house was empty, hardly ever happens!) not much about but came up behind a car doing 60 (clear day, no rain) with an utterly clear inside lane. I sat behind him for a while, I then gave him a flash which I hate doing but sometimes it wakes people up. He still didn't move but flashed his right hand indicator. No right turn for at least 6 miles at the next roundabout, so I slowly moved over to lane 1 and undertook him. Looking back he was flashing me and waving his fist, I have no idea of the rational he was using for needing to be in the right hand lane.