A vehicle closure locking system comprising person sensing means, authorization device detection means and a controller, the sensing means being capable of determining whether a person is located in the vehicle and the authorization device detection means being capable of detecting the presence of a co-operating authorization device within the vehicle, wherein the controller is programmed to instruct the detection means and sensing means to commence detecting and sensing respectively in response to a predetermined event and is further programmed to control the locked state of vehicle closure(s) in response to signals supplied periodically by the sensing means and signals supplied periodically by the authorization device detection means.