Recently there has been a renaissance in the investigation of materials which simultaneously exhibit magnetic and electric ordering with these materials expected to find application as sensors, data storage and microelectronics. We have recently synthesised a new material, Ba4Dy0.87Nb10O30, based on the tetragonal tungsten bronze structure which exhibits antiferromagnetic ordering (TN ~165 K) and ferroelectric ordering (Tc ~ 490 K). An anomaly in the The dielectric data also observed just above room temperature posiibly indicative of an incommensurate - commensurate phase transition. It is proposed to collect variable temperature diffraction data on this material between room temperature and approximately 1200 K with the aim of elucidating the phase transitions and understanding the origins of the dipolar response in this material.