The least powerful and relevant portion of the city government and a holdover from the beginning of the Empire, the Goodly Chamber is where all nobles of Horizon in good standing meet to debate the issues of the day. In many ways, then, it's like the Houses of Parliament but without the abilty to enact laws, though they do vote on motions: "This Chamber believes that..." and what not. They are mainly there to advise the Mayor, and Colonel Zero regards them as a useful barometer for testing the mood of the aristocracy.
The heads of the aristocratic families spend a fair amount of time at the Chamber. Whilst the Chamber itself is a mere talking shop, it provides a handy opportunity for members to meet one another and talk about matters of mutual interest. The really interesting stuff happens in the select committees (some of whom were established decades ago and have long past abandoned their original purview to pursue their own different agenda), and in the small cliques who meet informally for their own private purposes. Two such cliques are the Gentleman's Cause and the Old Club.
Each member of the Goodly Chamber receives an allocation of office space and a fund to pay for secretaries and various assistants. These employees fall into two sorts: pen-pushers who are there to get in the way of people who want to meet with MGCs and make the process of acquiring appointments as difficult and time-consuming as possible, and efficient aides who chat with the people the MGCs *do* actually want to talk to.
The head of the Goodly Chamber is given the ostentatious (and meaningless title) of First Lord of the Roads, and represents the Goodly Chamber in the Mayor's Privy Council. (The title dates from a time when the head of the Goodly Chamber was responsible for the Imperial Legion patrols on the roads, these patrols having been instituted initially to keep the roads safe for Goodly Chamber members...)