In the 1980s, the small anarchist group London Greenpeace - not related to Greenpeace International - produced a leaflet, "What's wrong with McDonald's?," about the poor nutritional value of McDonald's food, low wages of workers and environmental impacts of beef production, among other issues. McDonald's top management, being highly sensitive to criticism, hired two separate security firms to collect information on the group. Each of the firms hired individuals to infiltrate the activist group - which wasn't hard.
Because London Greenpeace had only a few members, the new recruits - the infiltrators - were welcomed; they provided energy for campaigning on various issues. At some meetings, there were several infiltrators attending, a good proportion of the attendance. The infiltrators produced reports for McDonald's, including detailed comments about each person involved. Because the two security firms didn't know about each other's operation, they reported on each other's infiltrators.