Chatham House Rule
The Chaham House website defines the Chatham House Rule as "When a meeting, or part thereof, is held under the Chatham House Rule, participants are free to use the information received, but neither the identity nor the affiliation of the speaker(s), nor that of any other participant, may be revealed". There is only one Chatham House Rule.
This is designed to allow people present at a meeting to be open in discussion without having to watch their back or being faced with differences between their personal views and those of their organisation.
Chatham House is a London based independent organisation set up in 1920 to facilitate discussion. The rule was devised in 1927 with refinements added in 1992 and 2002