This is a weighty tome (800 plus pages) and the authoritative history of perhaps the least glamorous of the U.K.’s principal security services. However, the facts illustrated in this book clearly demonstrates the critical role GCHQ plays in national security and perhaps one could argue is more relevant and more important than its more glamorous siblings, MI5 and MI6. From its incept in the early twentieth century we see the heights reached by Bletchley Park, the immediate forerunner to the (renaming) creation of GCHQ. The success of cracking the Nazi Germany Enigma code by computer-creating cryptographer heroes such as the now famous Alan Turing, is perhaps the height of the glamour. Post WW2 Bletchley Park staff were transferred over to a permanent base in rural Gloucestershire. Cheltenham later housed the service in the legendary doughnut, a purpose built facility that can rival James Bond’s flash new Thames-side MI6 HQ. The main division of labour at GCHQ falls into two branches – SIGINT and COMINT. Mathematicians are well sought for their crypto-analytic skills and GCHQ also encourages linguistically skilled talent. Most workers tend to stay in the organisation until retirement although the pay rates can be rather low and promotion opportunities thin on the ground. However, job satisfaction exists with interesting, varied, intellectually stimulating and critically important jobs. As well as skilled university recruits, a lot of workers are recruited in the administrative divisions and women have always been treated on a more or less level par with their male colleagues. The initial post WW2 focus on the agency was for targeting Russia, with linguists retraining and as much as 90% of the interceptions being directed to behind the Iron Curtain. GCHQ had success against the Soviet Union to a degree much more than HUMINT counterparts. MI5 and MI6 were often left lagging in comparison with KGB master spies. GCHQ has developed and is almost totally integrated with the American equivalent of signals intelligence, the NSA (National Security Agency) in the United States of America. Intelligence sharing in the secret UKUSA handshake agreement allowed all but the most politically sensitive data between the two nations to be completely shared. Five Eyes (including Commonwealth partners, Canada, Australia and New Zealand) is also important as is co-working with NATO allies but the USA with its larger budget and technological dominance has really been an asset to GCHQ development and from their point of view the NSA appreciates the skilled dedication of more traditional and experienced British siginters. As the twentieth century progressed, the digital age continued to rapidly develop on a global scale. GCHQ has to constantly adapt and master new communications technologies and acquire the latest state of the art equipment, necessary to maintain Britain’s post-imperial role as a primary global power. Enemies also change and Germans have given way to Soviets, the collapse of the USSR after the fall of the Berlin Wall, leading towards an internet dominated age where Islamic Salafi Jihadists strike terror in Western democracies and rising China sends an unleashed horde of cyberattackers, their quest to steal Western technology and disrupt libertarian values in their global competitors. The internet is a revolution and there is a demand for the public to be protected. In recent years GCHQ has emerged from the shadows and reluctantly revealed some of its clandestine secrets and the Directors of the present day have a need to be media savvy as well as being able to cloak and dagger brief the politicians and its foreign office and military masters. I found the details of the trade union problems in the 1970s to be surprising and interesting and can understand why unionisation was banned at GCHQ as a result of protecting national security. The most memorable chapter of the book was the case studies on Palestine (Israel), Konfrontasi (Indonesia) and Falklands conflict (Argentina). Being a linguist experienced in Mandarin Chinese, Arabic and Russian, someone who is techwise and also keen on protecting the nation and Commonwealth and allies of the U.K., and with the doughnut being half hour train ride away, I have written to them on multiple occasions, seeking some form of mutually beneficial employment but alas, the door is firmly closed and I have not heard but a peep emanating from the elusive GCHQ. Interesting book though, and well-researched and written in detail. Recommend.