Sir David Omand, GCB, was previously UK security and intelligence coordinator, permanent secretary of the UK Home Office, and director of GCHQ, the UK signals intelligence and cyber security agency. He is the author of Securing the State.

Mark Phythian is professor of politics in the School of History, Politics and International Relations at the University of Leicester and coeditor of the journal Intelligence and National Security. He is coauthor of Intelligence in an Insecure World and has nearly a dozen other books to his name.