The Prussian blue analogue K0.4Fe4[Cr(CN)6]2.8.16H2O (1) is a soft ferromagnet at ambient pressure with a critical temperature (Tc) of 19 K. Bridging cyanides are oriented in the sense Cr(3+)-C-N-Fe(2+), while magnetic measurements imply that the Fe2+ ions are all in the high-spin state. At 1.2 GPa Tc drops to 13 K and the saturation value of the magnetisation is reduced to 50% of its ambient-pressure value. It is thought that ~half the bridges isomerise to Cr(3+)-N-C-Fe(2+), while the change from N to C ligation causes a spin cross-over to the low spin state at the Fe2+ centres. The aim of the present beam-time request is to obtain crystallographic confirmation of the flipping process.