Changes

After the English Civil war in the 1650s, Oliver Cromwell realized there needed to be greater control of the postal service, which became the primary way in which many plots were orchestrated. Thus, the Post Office, under John Thurloe, increased letter surveillance to help uncover plots against Cromwell. This was development by Thurloe also among included the earliest known usage of mathematicians as dedicated, state-sponsored code breakers, where Thurloe employed mathematicians from Oxford, such as John Wallis, to decipher conspiracies (Figure 2). This was also a period where a form of 'fake news" ' was instigated by the state by controlling the flow of information in mass media. While the state increased its efforts in trying to infiltrate various groups, including Catholics and potential conspirators, the state attempted to mislead in some news so as to help disrupt potential threat threast and ability to organize for hostile groups. The press, at times, could be used as a coded messaging system to conspirators.<ref>For more on Crowell's use of spies and particularly spying on the Post Office, see: Smith, G. (2011) <i>Royalist agents, conspirators and spies: their role in the British Civil Wars, 1640-1660</i>. Farnham, Surrey ; Burlington, VT, Ashgate.</ref>

Espionage, domestically and abroad, continued to be controlled by a spymaster often in the service of the monarch, that is after the monarchy was restored after the death of Cromwell. Well after Thurloe, a central spymaster, often the Secertary Secretary of State, would control both domestic and foreign spy networks. After the threat of Catholic invasion subsided, spies began to be used more against the threats to the emerging British Empire. Namely, this was France before and during the Napoleonic wars. Throughout the 19th century, espionage continued to mostly use the structure developed in the 17th century. This meant there was increasingly high burden on a single figure in government responsible for domestic and foreign spies. As the British Empire expanded, so to did the needs of the British espionage services.<ref>For more on the development of spies particularly in the Napoleonic wars, see: Sparrow, E. (1999) <i>Secret service: British agents in France, 1792-1815</i>. Woodbridge, Suffolk, UK ; Rochester, NY, USA, Boydell Press.