The Secret Listeners

Title:                      The Secret Listeners

Author:                 Sinclair McKay

McKay, Sinclair (2012). The Secret Listeners: How The Y Service Intercepted German Codes For Bletchley Park. London: Aurum

LCCN:    2013375792

D810.S7 M39 2012


Date Posted:      November 6, 2015

Reviewed by Hayden Peake[1]

The ULTRA Secret[2] was the first of many books to describe the breaking of German codes during WWII. Each of them mentions that the messages decrypted came from a system of world-wide radio intercept stations. They do not, however, explain much about how the stations were established, the functions each performed, what the personnel were like, or the bureaucratic and organizational problems they overcame. The Secret Listeners fills the gap.

British author Sinclair McKay tells the WWII intercept side of story of what came to be called the Y Service—the term comes from pronouncing the abbreviation WI for wireless-intercept. Intercepting German radio traffic originated during WWI as a source for the British Room 40 and the Government Code and Cypher School responsible for breaking German codes. At the start of WWII, MI5 created the Radio Security Service (RSS), which was intended to detect German agents operating from England. When it turned out there weren’t any such agents, the intercept operators began tracking any German encrypted messages they could hear and sent them to Bletchley Park in case that might be of interest. When their efforts were dismissed as unnecessary, since that was not the RSS mission, Hugh Trevor-Roper and a colleague decided to try decrypting them themselves. They were successful and discovered that the traffic was from the Abwehr, the German military security service. When this was pointed out to Bletchley, Trevor-Roper was rebuked again for butting in, but his point had been made. The RSS was quickly subsumed under MI6, joining the Y Service, which took over the mission.

The Secret Listeners doesn’t dwell on the operational side of the Y Service activities. Instead, McKay describes the personnel involved and their selection criteria, their often unrelentingly tedious working conditions, and some of the clever techniques they employed. In the latter category he tells about the “Ghost Voices.” When operators became proficient in monitoring instructions to German pilots, they began interrupting instructions from German aviation control and giving pilots spurious orders to misdirect them and, in some cases, causing them to run out of fuel en route to a bogus target.

Although some of the names McKay mentions will be familiar to readers of WWII codebreaking history, most will not, and he uses their letters and reminiscences to give them long overdue recognition. The Secret Listeners is a story too long untold, and it is a valuable contribution to the intelligence literature.

[1] Peake, Hayden B. in The Intelligencer: Journal of U. S. Intelligence Studies (20, 1, Spring/Summer 2013, pp. 1143-115). Hayden Peake is the Curator of the CIA’s Historical Intelligence Collection. He has served in the Directorate of Science and Technology and the Directorate of Operations. Most of these reviews appeared in recent unclassified editions of CIA’s Studies in Intelligence. These and many other reviews and articles may be found on line at

[2] Winterbotham, Frederick William(1974). The Ultra Secret. London: Weidenfeld and Nicolson

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