Contact 21 (in-universe)

Richard Barnes, like all Contact 21 agents, kept up to date with all aspects of the Universal Secret Service through the Contact 21 page. (PROSE: Agents In Action)

When going to see Dr. Who and the Daleks at the cinema, Agent 671107 and their friend suspected some other audience members to be enemy agents after they correctly identified them as "junior Special Agents — perhaps Agents from Contact 21!". (PROSE: From Agent 671107)