But wider access brings with it a problem that the NHS has ignored--the threat of aggregation. At present, hospitals make do with relatively little security; after all, not many people will walk into a ward and steal a file from the note trolley. But once the records are aggregated into a database covering tens of millions of patients, that database will be a major target for data thieves, blackmailers, and others with less than altruistic motives. Evidence for this comes from the military, the banking industry, and the American health care system.