Current-controlled polarisation and wavelength switching in 1.3 μm GaInAsP ridge-waveguide twin-stripe (RWTS) lasers with a properly designed effective index profile is reported. In CW operation at room temperature, an output power of 4 mW can be switched from TM- to TE-polarisation with an extinction ratio of 15 dB by a control current of only 4 mA. The polarisation switching is accompanied by a wavelength shift of 17 nm. Under fast direct current modulation, intrinsic optical response times of less than 235 ps are obtained. A self-consistent analysis of the active lateral waveguide shows that the switching effect is based on the deformation of the TE-mode profile resulting from antiguiding controlled by a small injection current.