With national targets to reduce carbon emissions enforced by international accords, the UK's energy sector will move towards its low carbon future through political, societal and technological drivers. Three Transition Pathway narratives have been developed to describe three different evolutions of the UK energy sector out to 2050. This paper details two tools that have been combined to assess the robustness and rationale of these three energy futures. The future energy scenario assessment (FESA) tool is used to develop pathway specific large-scale generation mixes that meet expected demands on both a yearly and hourly time step basis. The multi-objective transmission reinforcement planning (MOTRiP) tool is used to generate a set of electrical network plans for the assessment of expected electrical infrastructure requirements, following the application of the future generation mixes to the current GB electrical transmission network. The results, detailed throughout this paper, demonstrate that the combination of FESA's detailed temporal analysis and MOTRiP's comprehensive geographical analysis provides a high-quality holistic examination of the Transition Pathways scenarios, assessing the need for national infrastructure reinforcements with the changing demand and generation patterns. (C) 2012 Elsevier Ltd. All rights reserved.