When John Morrill began his research career the most influential writing about mid-seventeenth-century England was essentially concerned with modernization, and, even in non-Marxist explanations, contained a strong strain of materialism. This was a prominent feature of the sometimes vituperative exchanges of the gentry debate, and John's first piece of extended writing about seventeenth-century England was written in response to that controversy; it was a long essay, composed during a summer vacation, which examined the relationship between the fortunes of particular gentry families and their Civil War allegiance. His interest in local realities, however, quickly gave rise to dissatisfaction with the broad categories of analysis with which the gentry controversy was engaged. By the time that he published the monograph based on his Oxford D.Phil. thesis, in 1974, he concluded (among other things) that ‘the particular situation in Cheshire diffracted the conflicts between King and Parliament into an individual and specific pattern. As a result all rigid, generalized explanations, particularly of the socio-economic kind, are unhelpful if not downright misleading.’ A desire to do better than these generalizations has driven his work ever since, and has thereby provided a huge stimulus to scholars of early modern England.

His doctoral study of Cheshire marked the beginning of the first of three overlapping but distinct phases in the development of his work, in each of which he has been a leading figure.