This article studies robustness in the positive feedback control of negative imaginary systems including poles at the origin using an integral resonant controller. The paper first presents some self-explanatory fundamentals of negative imaginary systems and then, robustness analysis methodology for the positive feedback interconnections of negative imaginary systems is briefly illustrated. An illustrative physical example of the class of negative imaginary systems corresponding to the train system is presented to demonstrate the robustness of negative imaginary feedback control systems.