[en] The effect of the (γn) channel on threshold π^-p scattering is considered. The symmetric 3 x 3 matrix of s-wave scattering amplitudes is written in terms of the components of a real symmetric 3 x 3 matrix which can be expanded in a power series in q². The behaviour near the π^-p threshold of the cross-sections for the processes π^-p →π⁰n and π^-p→γn is obtained and the Panofsky ratio in flight is calculated. The 2 x 2 matrix of s-wave scattering amplitudes for the open channels (π⁰n), (γn) below the π^-p threshold is also obtained and shown to be unitary. The theory of the Panofsky ratio for the decay of the π^-p 1s state is developed. (Auth.)