We wish to investigate a new series of materials in which manganese in benavidesite, MnPb4Sb6S14, is progressively replaced by iron, leading to jamesonite at complete substitution. Solid-solution behaviour is found throughout whilst transport property measurements demonstrate that the resistivity of the p-type semiconductors decreases by many orders of magnitude as the iron content increases. Both end members order magnetically at low temperatures, although the reported magnetic structures differ in their details. We propose to exploit the high contrast between iron and manganese to explore the possibility of cation ordering in the mixed phases. We will also investigate changes in magnetic structure and the variation of the ordered moment as the degree of electron localisation, indicated by the changes in the transport properties, increases across the solid solution.