How has privilege been expanded to protect reports on parliamentary proceedings?

Cases also developed by analogy with recognized occasions categorized as privileged. Protection of reports on parliamentary proceedings developed from extension of the principles applicable to accurate reports of judicial proceedings. The public interest in all matters relating to the conduct of public servants and the discharge of their duties was such that the advantage to the community at large from a fair and accurate report of parliamentary proceedings outweighed any injury resulting from the publication. Cockburn C.J. explained the expansion of the privilege in this situation in Wason v. Walter, supra. at 93: To us it seems clear that the principles on which the publication of reports of the proceedings of courts of justice have been held to be privileged apply to the reports of parliamentary proceedings. The analogy between the two cases is in every respect complete. If the rule has never been applied to the reports of parliamentary proceedings till now, we must assume that it is only because the occasion has never before arisen. If the principles which are the foundation of the privilege in the one case are applicable to the other, we must not hesitate to apply them, more especially when by so doing we avoid the glaring anomaly and injustice to which we have before adverted. Whatever disadvantages attach to a system of unwritten law, and of these we are fully sensible, it has at least this advantage, that its elasticity enables those who administer it to adapt it to the varying conditions of society, and to the requirements and habits of the age in which we live, so as to avoid the inconsistencies and injustice which arise when the law is no longer in harmony with the wants and usages and interests of the generation to which it is immediately applied. In so doing, he rejected the argument that expansion of occasions of privilege could only occur by act of the legislature.