All these things that I have done

Are you sure? I don't have the reference to hand, but I'm sure that studies of IQ and class carried out in the last 50 years or so have found a social mobility of at least 25%, and that IQ was a good predictor of class as an adult. Of course, IQ is by no means independent of childhood class, and I don't want to go into its faults as a measure of anything useful, but 'very restricted' seems a harsh assessment if my memory of the figures is correct. Lower than it should be in an ideal world? But what criteria would determine what class someone should be in an ideal world? And remember that social mobility is not just in one direction. I tend to agree with Sonia.