Shirley Williams.
In the late 1960s she was Minister of Education in the labour Government. She imposed "comprehensive education" on everyone. Prior to those days, bright kids of whatever social class went to Grammar Schools, which were good for academic studies (and also for cricket

. Ordinary and dull kids went to Secondary Modern schools, or Secondary technical schools, which at worst were like comprehensives and at best taught them something useful that led on to apprenticeships and practical jobs.
The effect of this political imposition was to destroy good schools and replace them with mediocre ones.
At the same time, fashionable educational theories were put into practice in place of the "three Rs" and moral values.
As for social deprivation, it is as old as the hills, nothing new about the 1970s in that corner. There have always been some people who are relatively poor, some who are about average, and others who are well off. The only really new thing in the 1970s was the brief but disastrous fashion for building tower blocks for families to live in in the cities. Oh yes, and the creation of the profession of social worker and (then) fashionable university courses in "sociology" at places like Sussex University. Some changes in the perception of social deprivation by middle-class non-deprived educated folk, as distinct from the actual experience of it by the poor, resulted from the invention and expansion of sociology.
Google "Shirley Williams", "comprehensive schools", "sociloogy" and "Professor Titmuss" for more info.