Chatham House Rule
As an example, consider one particularly contentious 1927 session at the Royal Institute of International Affairs that took place at Chatham House in the center of London's Westminster. It originated an idea now used worldwide - the famous Chatham House Rule. Under its most recent revision (2002), the Rule allows the participants of a meeting to use the information received there, but prohibits them from revealing the identity or affiliation of anyone else present.
The Chatham Rule also governed the meetings I attended at Windsor Castle outside London from a recent Friday through to the early-morning hours of the following Monday. These meetings were the annual consultations of the Queen's Windsor Energy Group, which were meant to be private, high-level, discretionary advisories. This is one of the few "old boys" clubs left in the world where talk can translate directly into action.