I am afraid, Keith, that this is not a convincing argument. It is factually incorrect to claim that all historiography before the 1970s offered some kind of explanation founded on a relationship between the 'base' of English society and its 'superstructure' as a reading of Hume, Mackintosh, Hallam, Macaulay and Trevelyan will show.
It is a matter of debate when the heyday of British capitalism occurred but no one has yet shown how this shaped Whig historiography or made it more convincing. In any case, the origins of 'revisionism' lie not in the 1970s, whether early or late, but in the late-1960s when it was increasingly obvious that the kind of deterministic explanations offered by Tawney, Hill, Stone and others were unsustainable because they were at variance with the surviving evidence.
By 1973, the work of 'revision' as Ted Rabb would describe it and the reaction against the kind of history being written by Stone and Hill wa s well under way. This was long before Ronald Reagan and Margaret Thatcher reached the front rank of politics on either side of the Atlantic and long before John Adamson began his work on the 1640s.
No so -called revisionist poured scorn on Marxist theory nor has Adamson downplayed the role of Oliver Cromwell. You should read the latter's essay on 'Oliver Cromwell and the Long Parliament' in John Morrill, ed., Oliver Cromwell and the English Revolution (Longman. 1990) as penance. However one defines the political preferences of those you regard as 'revisionists', they were not predominantly or even obliquely right-wing.
Tristram Hunt and Simon Schama are, moreover, hardly specialists in seventeenth-century English history. I ought to add that Kishlansky's attacks on Adamson in and after 1990 had a great deal more to do with academic politics than your account allows.
There was no requirement on Adamson to preface his study of the political role of the peerage in the 1640s with an analysis of the class composition of the gentry or of its relationship with the Stuart Crown: that would have meant giving up his priorities in research and writing to address a long obsolete Marxist agenda. It was for him to write as he chose and to investigate the issues he wanted to examine. That is the right and duty of every historian. But do not suppose that he is or has been unaware of the connections between the members of the Junto in 1640-1642 and of the grandees later in the decade with the worlds of London mercantile and artisan politics.
The novelty of his work lies in the revelations he has already made about such links and that he will make in subsequent publications. He has reshaped the historiography of the period already and will continue to do so because his work rests on secure evidential foundations, not on a political approach to the past.