An adjustable linkage (6) for an actuator control mechanism has a resilient cantilevered frame (1) to which is assembled at least one lever arrangement (7, 17) for connecting and transmitting the displacement of a control means (15, 19) to operate an actuator device. A first end (5A) of the frame is adapted for contact with a housing (9A) of the control means whilst a second end (3) of the frame can be assembled to a head-stock extension arm (12) of the actuator device. The at least one lever arrangement (7, 17) is pivotably connected to the frame (1) between the first and second ends. The arrangement is such that the linkage is able to self adjust to accommodate relative dimensional variations between the control means housing (9A) and the head-stock extension arm. The linkage is particularly suited for use as part of mechanism for controlling actuation of a cistern discharge valve.