Yasmin Jain, a senior policy analyst in the National Institute for Civil Liberties, told VICE News that, “I don’t see why someone with an anti-establishment political bent would join a group engaged in that sort of activity.”

“It certainly isn’t an ideal situation for the police to be working on,” she cautioned.

Jain added that, “It clearly puts the police in an untenable position. People in a group like that need to be more careful about their communications. I understand why [the police] are worried but I think it is a step too far.”

“When asked about her motivations, Ms. Yasmin said she was just curious to see what police could do to prevent an act of terrorism, particularly given that the police are not aware of any threats against her.”

The police did not respond to requests for a comment.

The case involving the members of the group was first reported by Breitbart London in May 2015 following reports of their activities via social media. A string of tweets from the group’s leader and deputy, which appeared to show her having a drink by an open window had prompted calls for a full investigation by the Home Office.

The investigation was later halted by Home Secretary Amber Rudd last year following criticism of the police’s conduct from Conservative peers, which the Home Secretary described as a “minor incident”.

Police officers in New York were forced to halt an investigation after the group threatened to attack cops on a subway over political differences, Breitbart London reported last year. A group of activists from the anti-fascist group Antifa were also reportedly planning to target two police officers in the wake of Trump’s election during the New Year’s Eve celebrations.

The NYPD reportedly carried out a probe after being alerted to possible threat by anti-fascist activists.

Follow Jack Montgomery on Twitter: @JackBMontgomery