The film, published on 14 November on The Guardian website, shows the officer asking an activist to attend meetings at the University of Cambridge students’ union and pass on information to him about the issues discussed.
The officer said that he was looking for information on several groups, including UK Uncut, a campaign against tax avoidance and government tax, and Unite Against Fascism, as well as the anti-fracking movement.
He said that he wanted details about any protests being planned, as well as the names of people going to protest, how they would travel to the event, and the licence plates of any vehicles involved. He also asked the activist to look out for updates from groups on Facebook.
The activist has not been a student at the university, according to The Guardian.
The Cambridge University Students’ Union said that it was “alarmed” by the news and found it “absurd” that its members would be the focus of these investigations.
It said: “CUSU has always constructively engaged with the police when planning or supporting protests and demonstrations.”
The union called the tactics “intrusive” and said that they wasted time targeting groups “which are involved in making important and positive change in our society”.
A Cambridgeshire Police spokeswoman said: “Officers use covert tactics to gather intelligence, in accordance with the law, to assist in the prevention and detection of criminal activity.”
During the meeting, the activist asked the officer whether he would be interested in information about Cambridge Defend Education, a group that has protested on tuition fees and education cuts. The officer said that was the “sort of thing” he would be looking for.
A statement on the Cambridge Defend Education website said that it was “not surprised” to find itself the subject of police surveillance.
“This constitutes part of a wider attempt by the police, university management and the government to criminalise and suppress dissent within universities across the country,” it said.
CDE said that it would refuse to be intimidated by the tactics, which it called “coercive and underhand”.
Meanwhile, regional secretary of the Unite union said that the police were using a “sledgehammer to crack a non-existent nut”.
He added that the events were not about national security but a “bungled attempt to spy” on students’ healthy interested in politics, social justice and going on demonstrations. The University of Cambridge declined to comment, and said that it was a police matter.