Her entry in The Oxford Dictionary of National Biography describes Susan Isaacs as ‘the greatest influence on British education in the twentieth century.’ Whether or not this claim is justified, there is no doubt that so-called child-centred education became a much more powerful element in educational practice during the twentieth century and that, as far as infant and primary education were concerned, Susan Isaacs was highly influential in producing this change. The 1967 Plowden Report on primary education was largely built on her views. The reaction to extreme progressive views in the fourth quarter of the twentieth century with increasingly prescriptive curricular changes would not have been to her liking.
In contrast, the last quarter of the twentieth century saw a strong confirmation in psychoanalytic circles of the Kleinian theory Susan Isaacs had supported. The Tavistock Clinic, with its emphasis on early infancy and the importance of fantasy and play in personality development became the pre-eminent centre for psychoanalytic research and teaching in the UK.
However, the major changes in the field of child development that occurred in the later part of the twentieth century, namely the explosion in the application of the neurosciences and genetics owed little or nothing to Susan Isaacs. Further, it cannot be said that she contributed to the growth of interest in studies evaluating the effectiveness of different forms of therapy.