In view of the negative connotations associated with conspiracy theories, what have been the effects of the term's entry into popular vocabulary in the second half of the twentieth century? Has the ascendancy of the term “conspiracy theory” been correlated with a reluctance to allege conspiracy? In this article, the authors use Hansard, the record of British parliamentary debates, as a source of empirical data in demonstrating a significant and steady reduction in the number of conspiracy claims advanced in parliament; a pattern consistent with the broader marginalization of conspiracy rhetoric. This trend was reinforced by a trope that established itself in the 1980s and juxtaposed “conspiracies” with “cock-ups.” The British expression “cock-up” denotes a blunder or act of incompetence. In the second part of this article, the authors argue that the preference for “cock-up theories” over “conspiracy theories” reflects how a policy geared towards privatization and deregulation tended to characterize government action in terms of incompetence, and not of malfeasance.