A model for a beam-driven plasma neutraliser for a 1MeV, 40A beam of D- ions is presented and is based on the dimensions of the ITER gas neutraliser. For the beam-driven plasma neutraliser there is no need for an external power source for producing and sustaining the plasma. Instead the use of high magnetic fields is employed for plasma confinement, which can be produced by arrangement of bar magnets in Halbach arrays around the neutraliser vessel. Magnetic modelling is presented to verify the high cusp fields that can be achieved. The model is an extension of an existing plasma neutraliser model with updated cross-sections, a defined gas profile and magnetic confinement at the entrance and exit of the neutraliser, in order to prevent plasma leakage but still allowing beam propagation with minimal net deflection. The model calculates the beam current fractions and ionisation currents at each step along the length, and at the end of each cycle the induced plasma density and temperature are calculated until convergence is reached. The cusp strength, separation and gas flow rate can be varied and the effects of these parameters on the plasma density and neutralisation fraction are presented. There is currently no data for beam-driven plasma neutralisers therefore possible experiments for benchmarking data are also discussed.