Of all political notions floating about the seventeenth century, perhaps the most seductive was the sovereignty of parliament. By that idea is meant precisely this: that parliament is the final arbiter of whatever is undertaken by the monarch and nation, and the actions of the executive and the judges are subject to parliament's rule and, if need be, reversal. Such a view had its sixteenth-century origins, before Jean Bodin elevated the concept of ‘sovereignty’ itself to a political commonplace. Famously, Henry VIII himself said his ‘estate royal’ was greatest ‘in the time of Parliament’; Sir Thomas Smith held the parliament was the ‘most high and absolute power of the realme’. Whether, though, the notion of parliamentary sovereignty was mere political boilerplate or a contentious and, indeed, a revolutionary doctrine depended entirely upon what one held to be the composition of a parliament. Both Henry and Smith – and, following them, the overwhelming preponderance of informed pre-Civil War opinion – thought a parliament included the king as a fundamental part. Without the king, the two houses were no parliament. Yet common if unthinking usage held that the Lords and Commons alone constituted the parliament. King versus parliament, royalists versus Roundheads – sophistications or sophistries aside, that was what the conflict seemed to be about.

Of course, those self-serving and conscience-assuaging equivocations had their uses.