The Angry Brigade was a radical political group responsible for a series of bomb attacks in England between 1970 and 1972. It was not spied on by the Special Demonstration Squad but was targeted by Special Branch.

Using small bombs, the Angry Brigade targeted banks, embassies, a BBC outside-broadcast vehicle, and the homes of Conservative members of parliament.
In total, police attributed 25 bombings to the Angry Brigade. Eight people were arrested after a series of raids and a police operation that included Special Branch. Those who stood trial became known as the Stoke Newington Eight.
Four, including Stuart Christie, were acquitted. However, John Barker, Hilary Creek, Anna Mendelssohn and Jim Greenfield were convicted on majority verdicts, and sentenced to ten years.
HN325 Conrad Dixon and HN3093 Roy Creamer were involved in this investigation, after they had left the SDS.
Details about this can be found in their respective profiles.A number of SDS reports mention the Angry Brigade in passing but none suggest that the unit successfully targeted the group. In addition, SDS annual reports invoked Angry Brigade activities to justify the unit’s surveillance of anarchists.
Sources
Gordon Carr: The Angry Brigade.
Stuart Christie: Granny made me an anarchist.