Mark Kennedy, a former undercover police officer, was involved in infiltrating environmental and activist groups, including those participating in climate camps. His activities spanned several years, during which he assumed the alias "Mark Stone." Kennedy's undercover work involved gathering intelligence on environmental activists and their activities, which included protests and direct actions related to climate change and environmental issues.

Kennedy's infiltration was part of a broader police operation to monitor and manage protest activities. However, his involvement became controversial due to the depth of his infiltration, which included forming close personal relationships with activists. The revelation of his true identity and role as an undercover officer led to significant public outcry and debate over the ethics and oversight of undercover policing in the UK. The scandal also prompted reviews and changes in how undercover operations were conducted, particularly concerning the rights and privacy of individuals involved in activism.