Abstract: A permanent magnet electrical machine comprises a first substantially planar member (9, 10) and a second substantially planar member (3) arranged substantially parallel to the first substantially planar member. The first and second members are rotatable relative to each other about a common axis substantially perpendicular to the planes of the first and second members. The first member (9, 10) is provided with an annular array of permanent magnets (7, 8) coaxial with the common axis and configured to provide a substantially axial magnetic field passing through the second member. The second member (3) is provided with a first annular array of flat coils (1) coaxial with the common axis and arranged substantially side-by-side in a first layer and with a second annular array of flat coils (2) coaxial with the common axis and arranged substantially side-by-side in a second layer. The coils (2) of the second array are offset in a circumferential direction relative to the coils (1) of the first array.