A rotating electrical machine is disclosed, the machine comprising a stator 14, 52 and a rotor 10, 50 arranged to rotate inside the stator. The rotor comprises a plurality of permanent magnets 28, 30, 54 arranged to produce a radial magnetic flux in an airgap between the rotor and the stator. The machine also comprises a stationary excitation coil 34, 46, 66. The rotor comprises a plurality of low reluctance elements 32, 58. A current through the stationary excitation coil causes a magnetic flux to be established in a magnetic flux path which passes into the rotor through a first low reluctance element and out of the rotor through a second low reluctance element, which magnetic flux combines with the radial magnetic flux produced by the permanent magnets in the airgap. This arrangement can allow control of the field within a permanent magnet radial flux machine.