In 1972, Rutter published 'Maternal Deprivation Reassessed', which New Society describes as "a classic in the field of child care" in which he evaluated the maternal deprivation hypothesis propounded by Dr John Bowlby in 1951. Bowlby had proposed that “the infant and young child should experience a warm, intimate, and continuous relationship with his mother (or permanent mother substitute) in which both find satisfaction and enjoyment” and that not to do so may have significant and irreversible mental health consequences. This theory was both influential and controversial. Rutter made a significant contribution, his 1981 monograph and other papers (Rutter 1972; Rutter 1979) comprising the definitive empirical evaluation and update of Bowlby's early work on maternal deprivation. He amassed further evidence, addressed the many different underlying social and psychological mechanisms and showed that Bowlby was only partially right and often for the wrong reasons. Rutter highlighted the other forms of deprivation found in institutional care, the complexity of separation distress and suggested that anti-social behaviour was not linked to maternal deprivation as such but to family discord. The importance of these refinements of the maternal deprivation hypothesis was to reposition it as a "vulnerability factor" rather than a causative agent, with a number of varied influences determining which path a child will take.