Different variants of a bulk nanocrystalline bainitic steel will be measured using white beam neutrons to produce one spectrum per sample. These data will be used in Rietveld refinement to assess the crystal structure of the phases present in order to investigate whether the ferritic phase, usually taken to be body-centred cubic (BCC) is, in fact body-centred tetragonal (BCT). This investigation follows from a synchrotron XRD experiment which showed that the structure may be BCT. Four of the samples, which have been designed to be mroe resistant to thermal decomposition, will also be heated in-situ and diffraction data will be taken continually. This will allow any microstructural changes to be tracked during the heat treatment. This will inform future alloy design with the aim of producing an alloy which may be used at elevated temperatures without any change in properties.