An electrical machine comprises: a first rotor , rotatable about axis, and having a first magnet arrangement on a first surface thereof; a second rotor, held with a first surface thereof adjacent the first surface of the first rotor and such that it cannot rotate about the first axis, but is rotatable about a second axis, and a second magnet arrangement on the first surface thereof; wherein the first and second magnet arrangements are such that rotation of the first rotor about the first axis causes rotation of the second rotor about the second axis. The first rotor is in the form of an at least partial hollow torus, with the first surface thereof being an internal surface. The second rotor is in the form of a cylinder, located within the hollow torus, with the first surface thereof being an external surface, such that the second axis is perpendicular to the first axis.