The Singing Sands by Josephine Tey - same thesis, possibly more enjoyable reading.
The Government says Britain has a serious social mobility problem, but a new Civitas report shows this is wrong. The Government’s social mobility strategy is based on a flawed understanding of the evidence. Social Mobility Delusions, by sociologist Peter Saunders, reviews the evidence on social mobility in Britain and finds: Social mobility is the norm in Britain, not the exception, and it occurs in both directions across the entire range of the occupational class structure.
