This bipartite paper flows out of the writing of a history of criminal justice and it attempts to resolve why so many state records of scholarly importance were destroyed in the latter half of the twentieth century. Since its foundation in 1838, the Public Record Office or PRO, later The National Archives, the chief repository of state papers, has confronted the problem of how to accommodate a remorselessly growing mass of documents. Shaped by periodic crises and bouts of anxious stocktaking, it has sought continually to develop effective ways of culling or ‘weeding’ the unwanted record. At the end of the Second World War, especially, the accumulation of papers had become so substantial that a new and radical organisation and methods analysis was to be applied by the Treasury to what was defined as a failed and antiquarian PRO. A committee under the chairmanship of Sir James Grigg elected to give primacy to reducing the volume of records. It turned its back on what it took to be the PRO’s discredited staff, techniques and ideology, although, ironically, it did warmly endorse the presumption of Sir Hilary Jenkinson, the PRO’s deputy keeper, that historians and archivists were quite incapable of identifying which records might become of future historical interest. Criteria of historical significance were as a result to be introduced slowly and belatedly, and only after Sir Hilary had departed. The outcome was to be a structural revolution that was driven principally by an imperative to save money and labour, conserve space and do away with as many records as possible, and much that was of scholarly interest has been lost in consequence.