Results are presented on a subset of proper motion data with |μ|≥0.04 arcsec yr −1 from the APM Proper Motion Project. Comparisons made with the NLTT catalogue show that the levels of contamination and incompleteness in this catalogue are consistent with the random measuring errors in the proper motions. No significant zero-point offset is found in the NLTT proper motions with respect to that defined by galaxies. Reduced proper motions in the four fields studied are found to be very effective in distinguishing between various stellar populations when combined with colour information