This is obviously the NuLab rebuttal strategy - I heard David Miliband coming out with it a week or so back, now Jim Murphy (who he ?) on the Today programme. (Health Warning - contains obligatory poke at the 'middle class')
"Yes, OK, social mobility is declining. But the study that shows it compares children born in the 1950s with children born in the 1970s. Those 70s children were at school in the 80s - under Thatcher."
Apparently something in the zeitgeist - the sight of unemployed parents, the 'grotesque level of child poverty' - so traumatised Thatcher's Children that they ceased to strive for a better future. More importantly, they did worse at school, hence the "increasing relationship between family income and educational attainment" of which the report complains.
If Messrs Miliband and Murphy were right, we should have seen social mobility plummeting in the 1950s and 1960s, as the hideous effects of the 20s and 30s depression kicked in. I believe child poverty was a tad more severe, too. My mother had two pairs of school shoes - one full of holes, with cardboard in the soles to protect her feet, in which she'd walk to school. When she got to Dynevor, she'd put on the 'best' pair. (Cries of 'Luxury !')
Yet the 50s and 60s were seen as times of increasing social mobility. Anything else happen in the 1980s ? Like the first generation to have a fully comprehensive school system ?