The Planck Surveyor mission has the potential to detect a very large sample of gravitationally-lensed galaxies and quasars. The exact size of the sample is expected to depend on the properties of distant dusty galaxies and quasars, the cosmological parameters, the observing wavelength and the sensitivity of the survey. However, several hundred lenses and several hundred thousand unlensed galaxies are expected at wavelengths of and . The most promising candidates can be selected for follow-up observations due to their submillimetre-wave colours determined in the Planck survey. Observations using FIRST will then determine their positions with sufficient accuracy for a high-resolution observation using a ground-based millimetre interferometer array to identify lensed arcs, rings or multiple images unequivocally. These follow-up observations could be carried out in several months of dedicated time on these facilities. The scientific rewards from further investigation of such a large unbiased sample would be very considerable, and it is difficult to see how such a sample could be compiled in any other waveband.