The Ruddlesden-Popper (RP) compounds An+1BnO3n+1 exhibit a broad range of technologically interesting properties such as high-Tc superconductivity, colossal magnetoresistance, metal to insulator transitions and ferroelectric / multiferroic ground states. In a study of one of these compounds Ca3Mn2O7, we have recently validated key predictions regarding a novel kind of ferroelectric mechanism which has a strong coupling to magnetism. We request now three days on PEARL to study the closely related phase Ca2MnO4 by high pressure Neutron powder diffraction, which has another intriguing property arising from the coupling between magnetism and strain. Our result will allow us to ascertain how this multiferroic interaction is mediated and ultimately how it may be optimised in this and similar systems such that it may ultimately have commercial application in the renewable energy sector.