Rail signalling in the UK has seen a move from mechanical lever frame boxes to entry and exit signalling, and on through to situating signallers within a visual display unit-based workstation environment. These developments have taken place in tandem with changes such as making the signallers more remote from their area of control and the introduction of automation. These changes have implications not only at a cognitive level for factors such as workload and situation awareness , but also at an organizational level, such as the shift away from traditional career progression, and the resulting implications for training and the development of expertise. Understanding the implications of the signalling interface and the design implementation of automation is critical in facilitating more effective performance, safety, and signaller well-being, as well as informing the design of future rail control systems. Bainbridge articulated a set of ironies of automation -unintended consequences of introducing automation that may not be beneficial to the overall system effectiveness. The work presented in this article uses a structured observation approach to examine behavioural indicators of the impact of automation, either as a successful tool to support signalling or as a source of some or all of the ironies noted by Bainbridge. The work was conducted over a period of 2 years, to investigate the effect of levels of automation on rail signallers' activity and workload as part of the EPSRC Rail Research UK B6 programme.