  We succeed in deriving an exact expression for the magnetic interaction of
neutrons and electrons including magneto-electric operators, allowed in the
absence of a centre of inversion symmetry. Central characters are a spin
anapole and an orbital (toroidal) analogue, in addition to familiar parity-even
operators. A simulation of neutron diffraction by antiferromagnetic copper
oxide makes full use of information inferred from a thorough investigation with
resonant x-ray Bragg diffraction.
