The nuclear and magnetic diffuse neutron scattering cross sections at 4.2K of a 4.7 at.% CuMn single crystal have been measured along the (100), (110), and (210) directions using polarisation analysis. The cross sections have been corrected for nuclear spin incoherent scattering by a similar measurement on a natural copper single crystal. The alloy is shown to be atomically random and, assuming g=2, the electronic spin per Mn atom S=1.77+or-0.05. The first-neighbour spin correlation is shown to be ferromagnetic.