Mi5 and Ireland, 1939-1945: The Official History

The book offers a comprehensive account of MI5's Irish section BIH, detailing its establishment and operations post-World War II. Declassified in 1999, it sheds light on the collaboration with Irish army intelligence and explores German espionage in Ireland during the war. Additionally, it reveals insights into British counterintelligence and codebreaking efforts against Axis threats via neutral Ireland. The text also critiques Irish security measures and intelligence strategies, providing a nuanced understanding of British intelligence in Ireland during this critical period.