"Prerogativa Regis, which if denied the status of a statute clearly had that of a declaration of the common law. Under their intensive scrutiny that document encompassed more than a medieval escheator would have found within it and thus Henry's feudal rights went well beyond those of his predecessors, but such results were achieved by the rigorous use of the law and logic rather than by their neglect. Admittedly the distinction was not one likely to be fully appreciated by landowners who now felt the full force of an expanded prerogative."