master of ceremonies, Beau Nash:

The master of ceremonies at an assembly sees that introductions are made, protocol is observed, gambling is kept under control (roll your eyes here) and that everyone has a ticket (usually delegated to someone else). Beau Nash was the most famous “emcee” at Bath, and with architect John Wood (elder and younger) and mayor Ralph Allen, made the reputation of Bath. In Persuasion, the emcee of the Lower Rooms, James King, is mentioned. He later became the emcee of the Upper Rooms.

Nash was called a dandy (Beau is an appellation) because of his trend-setting fashions. His position was largely self-proclaimed but real nonetheless.