Hybrid organic-inorganic perovskites are interesting candidates for a range of applications, from solar cells to light emitting diodes and lasers. For the latter applications the properties and efficiency are highly dependent on the morphology and particle size. Here we intend to characterise the temperature depedent phase behaviour of a fully deuterated sample of CD3ND3PbBr3 in bulk form. This will allow the influence of strain induced effects related to particle size to be investigated through modelling techniques. Our previous neutron studies have revealed that the published bulk phase behaviour is incomplete and we intend to correct this. A full understanding of the changes in the hydrogen bonding of the methylammonium cation with the perovskite framework as a function of temperature is likely to be of general interest for all applications of this family of materials.