An actuator comprising an output shaft and a control system configured to move the output shaft for actuating a component, wherein the control system comprises: a first drive system comprising a first movable component, which is a first nut; and a second drive system comprising a second movable component, which is a second nut; wherein the first component and the second component are connected to the output shaft, and each other, by a connecting member that moves with the first component and the second component to move the output shaft for actuating a component, and the control system further comprises: one or more bearing arrangements configured to permit movement of the connecting member by the first movable component or the second movable component upon failure, disengagement, shutdown or other stoppage of the second drive system or the first drive system, respectively; characterised in that: the first movable component is translatable along a first screw shaft of the first drive system, and the second movable component is translatable along a second screw shaft of the second drive system, wherein the first and second screw shafts (30,32) are located symmetrically on opposed sides of the output shaft; the first and second drive systems (20,22) each comprise a pair of electric motors (202,204,222,224) and each pair is located symmetrically on opposed sides of the output shaft and configured to rotate a respective screw shaft (30,32); and each electric motor (202,204,222,224) is configured to rotate a respective screw shaft (30,32) independently via a gear arrangement located at an axial end of the respective screw shaft (30,32). a first drive system comprising a first movable component, which is a first nut; and a second drive system comprising a second movable component, which is a second nut; wherein the first component and the second component are connected to the output shaft, and each other, by a connecting member that moves with the first component and the second component to move the output shaft for actuating a component, and the control system further comprises: one or more bearing arrangements configured to permit movement of the connecting member by the first movable component or the second movable component upon failure, disengagement, shutdown or other stoppage of the second drive system or the first drive system, respectively; characterised in that: the first movable component is translatable along a first screw shaft of the first drive system, and the second movable component is translatable along a second screw shaft of the second drive system, wherein the first and second screw shafts (30,32) are located symmetrically on opposed sides of the output shaft; the first and second drive systems (20,22) each comprise a pair of electric motors (202,204,222,224) and each pair is located symmetrically on opposed sides of the output shaft and configured to rotate a respective screw shaft (30,32); and each electric motor (202,204,222,224) is configured to rotate a respective screw shaft (30,32) independently via a gear arrangement located at an axial end of the respective screw shaft (30,32). one or more bearing arrangements configured to permit movement of the connecting member by the first movable component or the second movable component upon failure, disengagement, shutdown or other stoppage of the second drive system or the first drive system, respectively; characterised in that: the first movable component is translatable along a first screw shaft of the first drive system, and the second movable component is translatable along a second screw shaft of the second drive system, wherein the first and second screw shafts (30,32) are located symmetrically on opposed sides of the output shaft; the first and second drive systems (20,22) each comprise a pair of electric motors (202,204,222,224) and each pair is located symmetrically on opposed sides of the output shaft and configured to rotate a respective screw shaft (30,32); and each electric motor (202,204,222,224) is configured to rotate a respective screw shaft (30,32) independently via a gear arrangement located at an axial end of the respective screw shaft (30,32). the first movable component is translatable along a first screw shaft of the first drive system, and the second movable component is translatable along a second screw shaft of the second drive system, wherein the first and second screw shafts (30,32) are located symmetrically on opposed sides of the output shaft; the first and second drive systems (20,22) each comprise a pair of electric motors (202,204,222,224) and each pair is located symmetrically on opposed sides of the output shaft and configured to rotate a respective screw shaft (30,32); and each electric motor (202,204,222,224) is configured to rotate a respective screw shaft (30,32) independently via a gear arrangement located at an axial end of the respective screw shaft (30,32).