Abstract: A security system and method of providing security in a retail environment or the like, comprising shopping trolleys associated with the retail enviroment fitted with security devices having a receive-only wireless receiver and a processor. The receiver receiving wireless signals transmitted from one or more transmitters located at various locations around the retail enviroment. By analyzing the wireless signals as it passes thereby, the processor of the security device may determine a location and/or a direction of travel of a shopping trolley to which it is fitted. In addition, an alarm signal may be raised if a predetermined signal or sequence of signals is detected.