Abstract: A rotary actuator comprises a stator structure defining a magnetisable pole piece and an angularly movable rotor structure which defines a pole element. The pole piece and pole element form part of a magnetic circuit and a winding is provided about a portion of the magnetic circuit defined by the rotor and stator structures. The faces of the pole piece or pole element which are presented to each other are provided with a slot or a cutaway portion which extends along at least part of the circumferential length of the face whereby a desired torque/angle characteristic is obtained.