Abstract: A lock apparatus including a cylinder lock and an actuation member configured to operate the cylinder lock via rotation of the actuation member with respect to a part of the cylinder lock, wherein: the cylinder lock includes a magnet, and the actuation member includes a smart actuation member circuit, the smart actuation member circuit including: one or more sensors (including one or more magnetic field sensors) configured to sense an action of the smart actuation member circuit with respect to the cylinder lock; and a processor or controller configured to receive information indicative of the sensed action from the or each sensor for use in determining a status of the cylinder lock. Furthermore, smart actuation member circuit, cylinder lock and method of fitting such a cylinder lock are claimed.