An electrosurgical instrument for the treatment of tissue includes a longitudinal instrument shaft having a central axis, an end effector at the distal end of the shaft, the end effector including at least one element movable between a first and a second position. An actuator includes a handle which reciprocates movement between a first and second actuator position, and an actuation wire associated with the actuator for movement. Movement of the actuator causes the wire to move the element between its first and second positions, the wire running longitudinally of the shaft offset on one side from the central axis of the shaft. Compensation wire is associated with the actuator, the compensation wire running longitudinally of the shaft and being offset on the opposite side of the central axis of the shaft to that of the actuation wire.
