Copper
The officials who turn Gold will into paperwork. Nothing in the Society happens without a Copper's stamp on it.
They are small people, in the sense the Golds intend, but as the Republic will discover their skills transfer very neatly. See Publius.
They have copper curls, and Reds call them Pennies. Timony cu Podginus, who runs the Lykos mine for the Society, is the first of them Darrow knows.
Coppers run the Society's bureaucracy and its courts of record. They are comparatively well off and thoroughly compromised, which makes them a common source of informers for both sides. After the old order wobbles, they prove very good at finding themselves essential to the new one.