Described herein is a method of determining a current location speed limit in a road vehicle (1) speed limit information system (20). The method comprises receiving (6): one or more signals corresponding to respective candidate speed limits (7); and one or more signals related to observed vehicle dynamics affecting changes (8) in one or more vehicles (1, 5) pre and post a most recently passed anticipated speed limit change location (2). It further comprises evaluating (9) the confidence of the different candidate speed limits (7) based on the signals related to observed vehicle dynamics affecting changes (8) and validating (10a) or discarding (10b) candidate speed limits (7) based on the evaluated confidences. A signal (13) corresponding to a highest confidence validated speed limit is output.