In 1978, Special Branch and Anti-Terrorist Squad arrested Iris Mills, Dafydd Ladd, Ronan Bennet, Stewart Carr Vincent Stevenson and Trevor Dawton. They were initially charged with conspiracy to cause explosions.
In the SDS Annual Report of 1978, it was claimed that intelligence from the unit led to the idntification and arrest of one of the accused, though there is no other evidence of this. A defendants' solidarity group was formed (referred to by the acronym 'PUNK' in Special Branch documents) which HN304 'Graham Coates' spied upon. HN3093 Roy Creamer was also involved in the investigation.
Commenting on the trial, prominent anarchist Stuart Christie said:
The only proof the government had for such "terrorist" activity was the possession of some weed killer, sugar, flour and electrical wire at Iris Mills' house (if that's all it takes for proof of one's "positive steps" to overthrow society, then there are millions of "terrorists" out there and the revolution is at hand). Seeing that this "conspiracy" charge was so silly that it jeopardized their case, the state dropped them in favour of the more everyday robbery charges.
Even on these less serious charges, the jury cleared the defendants. Justice King-Hamilton, enraged by the acquittals, refused to dismiss the jury and ordered them to return the following day for Stewart Carr's sentencing. Carr was one of the six comprising the original "Persons Unknown" group but pleaded guilty to the charges. Carr was sentenced to nine years in prison.