National Grid in its capacity as both a Transmission Owner and System Operator is experiencing changes in the network characteristics, brought about by changing patterns in generation, transmission and demand technology. This paper discusses some observations around network performance and shares some thinking on the opportunities and considerations for new technology solutions to contribute to a sustainable transmission system fit for tomorrow. The process of specifying and analysing new technology to mitigate voltage regulation, network fluctuations and system fault level is becoming increasingly complex against a greater range of network scenarios of shrinking synchronous inertia and response. While design and testing standards are still essential, issues around calibration and interoperability of control schemes for power electronic devices are becoming more critical. This paper attempts to highlight some of the areas requiring assessment where new technology for power system applications is being considered.