There is widespread interest in perovskite materials, with work traditionally focusing on simple oxide systems. In recent years, however, there has been growing interest in the synthesis, structural and property characterisation of mixed anion perovskites, e.g. oxide fluoride systems. A key problem is establishing the nature of any oxygen/fluorine ordering. In this proposal, we will acquire quality pair distribution function (PDF) data on a range of perovskite iron oxide fluorides with different F contents, with a view to establishing information on any local ordering.