I went yesterday to the launch of an important new book, Unequal Britain at Work.  Using surveys that go back about 20 years and more it documents changes in the way we work and how it is rewarded:  not just how we are paid, but  the quality of the job, measured in terms of intensity, discretion and so on. A crucial feature of the book, and of the presentations made by its editors, Francis Green, Alan Felstead and Duncan Gallie, is the attention it pays to groups usually considered marginal, especially  part-timers and the self-employed.  One of the overall conclusions is that there has been a fair degree of convergence on…