There is now a significant body of knowledge in systems engineering and it seems likely to be of benefit to those designing signalling and control systems. In this paper we will investigate whether this is the case. We will start with a description of some of the terminology in use. We will then go on to review good practice in systems engineering outside the rail sector. We will suggest that rail systems have some particular features that may justify some adaptation of the systems engineering approach. We will describe some current practice in railway systems engineering before drawing some conclusions regarding the implications for signalling and control systems.