We report on the first submillimetre wavelength spectral scan of the Orion A molecular cloud in the frequency range 342-463 GHz (0.88-0.65 mm) using the Queen Mary College Submillimetre Heterodyne Receiver at UKIRT. Twenty-eight molecular transitions were detected, the majority of these for the first time. The lines include transitions of CO, CS, HCN, HCO+, H2CO, H2CS, SO, SO2, CCH, SiO and CH3OH. Upper limits are reported for a number of lines including CO+ and the ground state transition of NH2. A number of the lines are surprisingly intense, and we will present maps of the relative distributions of HCO+, HCN, H2CO and CCH, which show striking differences in their spatial structures. We will present details of the excitation of a number of the lines based on the results from this survey.