Crosland implemented his policy through two notorious Department of Education circulars to education authorities. The first requested that all authorities submit plans for turning their education provision completely comprehensive, followed by a second circular which gave notice that education by selection should be ended. Labour rhetoric of the time reflected the misplaced idealism that surrounded comprehensive education, as when the 1964 manifesto declared 'grammar school education will be extended: in future no child will he denied the opportunity of benefiting from it through arbitrary selection at the age of 11', or the dismissal of the Eleven Plus as 'that barrier to educational opportunity', from the 1966 manifesto. Unfortunately, for many years, blind allegiance to egalitarian dogma was to prevent any rational or meaningful analysis of the comprehensive system, or to address its many weaknesses. The conclusion was reached that, as 'progressive' thinkers had wholeheartedly endorsed this system, it must, ipso facto, be regarded as near perfect. Thus any criticism could be dismissed as reactionary or elitist, without the need to be troubled by any debate or argument. The Conservative leadership of the time appeared content with this situation.
Advocates for comprehensive education did not limit their aims to just encouraging this new system. They also sought changes to teaching methods, the content of the syllabus and means for enforcing discipline. So streaming by ability was discouraged, to be replaced by mixed-ability teaching, in which both intelligent and dull children were grouped together in the same class. The thinking behind this was that weaker pupils would be provided with positive models of achievement and every child would be given the same opportunity. Moreover, it was argued that streaming benefited bright pupils at the expense of weak ones. Behavioural problems were more likely in the lower streams, where pupils had become demotivated by the knowledge that they were at the bottom. Again, no evidence was provided that pupils, whatever their intelligence, would receive an education better tailored to their needs, as a result of the abandonment of streaming. The motive was purely egalitarian, achieving the overarching goal of ensuring that all children received equal treatment. Such an outlook was also highly paternalistic since all decisions were placed in the hands of educational 'experts' who could impose their vision on the rest of society, regardless of what ordinary parents might want, and who were thus rendered powerless when trying to obtain the kind of education they thought best for their children.
A milestone in the development of 'progressive' education was the Plowden Report of 1967, which examined primary education. It advocated a 'child-centred' approach in which the curriculum emanated from the child's previous knowledge and interests rather than being imposed externally. Such methods demanded high levels of commitment and energy from teachers, as well as fundamental changes to teaching methods. The traditional classroom layout of desks all facing the teacher, who taught the whole class, was replaced by informal groups of tables, where the teacher would give individual pupils assistance in their voyage of discovery through the educational system. Learning by rote was out - self-fulfilment was in. With the demise of the Eleven Plus mixed ability teaching was extended from primary to secondary schools.
By the mid-1970s comprehensive schools, mixed ability teaching and child centred education were the prevailing orthodoxies in an educational establishment that was now under firm liberal control, although there were still pockets of resistance in some Tory controlled education authorities which had managed, against all the odds, to retain grammar schools. Labour returned to Government in 1974, and was again committed to abolishing all grammar schools and direct grant schools, as well as ending tax breaks for the public schools. This was the zenith of liberal confidence in their egalitarian educational doctrines. However, nemesis was just around the corner when the national media spotlight focussed on the William Tyndall School in Islington, where near anarchy had broken out as a result of the extreme leftist policies carried out by the teaching staff. Public and media discontent with the low achievement of many comprehensives now began to grow. Working class children, compelled to attend the local sink comprehensive, were the most badly affected, the very children the comprehensive system was created to help. Better off middle class parents, however, had more choice since they could move into the catchment area of successful schools, thereby forcing up house prices in these neighbourhoods. Labour Prime Minister James Callaghan called for a 'great debate' on education. Clearly, the utopian dream that comprehensive education was expected to deliver was still a long way off.
Meanwhile, discontent on the Right about the direction of education policy began to mount. In 1969, the first of the Black Papers on Education was published. These papers, there were five in total, were fiercely attacked as 'reactionary', a favourite term of abuse employed by liberals to denounce and marginalise heretical ideas. By the end of the 1970s comprehensive education was coming under increased attack by a more assertive Conservative party.