Which of the following options is not a power held exclusively by the Council of Lloyd's?

The management of all Lloyd's affairs is a responsibility that is shared among various bodies within Lloyd’s, rather than being held exclusively by the Council of Lloyd's. While the Council does play a significant role in overseeing the operations and strategic direction of Lloyd's, it is supported by the market's executive team and other governance bodies, such as the Franchise Board, which handle day-to-day management and operational decisions.

In contrast, the other options represent powers that the Council does hold exclusively. For instance, creating rules such as byelaws is a specific authority granted to the Council, enabling it to set regulations that all members must adhere to. Similarly, setting the business plan for the market and taking disciplinary action against members are powers that fall directly under the Council's jurisdiction, as these functions require a level of governance that only the Council can provide. Thus, the management of all Lloyd's affairs encompasses a broader range of responsibilities beyond those designated solely to the Council, which makes it the correct choice for this question.