Originally the name of a department of the Central Committee of the Communist Party of the Soviet Union responsible for political propaganda, in the context of the Inquiry it refers to one or more groups.
There were two separate activist groups around in the late 1960s and early 1970s respectively. The 1968 group was a Maoist-orientated 'radical information agency' based at 160 North Gower Street, central London and listed as a primary surveillance target in the 1970 SDS Annual Report.
From 1971, the SDS reported on an Agitprop at 248 Bethnal Green Road, East London, connected to the Angry Brigade. This iteration was anarchist and also the base of the Gay Liberation Front.
The 1971 Special Branch Annual Report suggests a continuity between the Gower St and Bethnal Green Road organisations, but this is likely to be an error.
There was also a totally seperate Socialist Workers Party offshoot (c.1978/79) with the same name.