MI8 For the American crytography group , see MI-8 . For the helicopter , see Mil Mi-8 MI8 , or Military Intelligence , section 8 , was a department of the British Directorate of Military Intelligence , part of the War Office . It was a British signals intelligence group in World War II . Also known as the Radio Security Service , it tracked radio broadcasts about German bombers during The Blitz . [ citation needed ] Signals intelligence in the UK is now performed by the Government Communications Headquarters ( GCHQ ) . See also MI5 MI6 United Kingdom Intelligence Agencies edit Current - Government Communications Headquarters  ( GCHQ ) | Security Service  ( MI5 ) | Secret Intelligence Service  ( MI6 ) | Defence Intelligence Staff  ( DIS ) | Serious Organised Crime Agency  ( SOCA ) | Joint Intelligence Committee  ( JIC ) Defunct Agencies - MI1 | MI2 | MI3 | MI4 | MI7 | MI8 | MI9 | MI10 | MI11 | MI12 | MI14 | MI15 | MI16 | MI17 | MI19  This cryptography -related article is a stub . You can help Wikipedia by expanding it .  This article related to the politics of the United Kingdom , or its predecessor states , is a stub . You can help Wikipedia by expanding it . This military article is a stub . You can help Wikipedia by expanding it . Categories : Articles with unsourced statements | Organizations in cryptography | Groups of World War II | United Kingdom intelligence agencies | Cryptography stubs | British politics stubs | Military stubs In other languages : Deutsch | Nederlands 