The discussion about last light is interesting but in the case of VH-UVC's last flight probably not all that relevant. The accident aircraft left Coffs mid-afternoon for Bankstown. Under no circumstance was that flight not going to include flight under Night VFR. After last light and in at least 'challenging conditions' the opportunity to land at Williamtown presented itself and was passed over. The definition of last light and the rules relevant to Night VFR did not appear to be in any way a factor in the planing or execution of the flight.