The soldier, publisher, and pamphleteer John Streater is a comparatively neglected political writer of the 1650s, who represents the turning of the dispersed Levellers to classical republicanism. In the 1650s he is seen as a brave and uncompromising voice of opposition. In the autumn of 1653 he was prosecuted by Cromwell for publishing a work entitled The grand politick informer. This article rediscovers this publication, identifies it as Streater's first newsbook, and explores its implications for Streater's career and canon. In 1654 Streater wrote two series of newsbooks which criticized the Protectorate in an oblique fashion. The grand politick informer, a work of unbridled ferocity, shows that Streater learned to tame his voice after his 1653 prosecution and imprisonment, and to couch his antagonism to the government in the language of classical allusion.