Flutter calculations were made on a fixed root model wing carrying a localised mass. Modes were calculated for the wing for certain conditions of restraint at the localised mass position, the choice of modes being based on observation of the behaviour of wind tunnel models under fluttering conditions. The general agreement between the calculations and experimental results was good and justified the extension of the calculations to conditions of localised mass loading that were not covered by experiment. The extended calculations show that there is an optimum spanwise position for a localised mass from the flutter point of view and, that this optimum position is related to the nodal line position in the overtone torsion mode of the bare wing. For values of localised mass parameters likely to occur in practice, flutter speeds can be estimated from calculations in a very limited number of modes, the choice of modes depending on the localised mass loading.