The UK is characterised by spatial inequality between and within regions, alongside an over-centralised asymmetric model of governance. In England especially, these features are stark, and throughout the last decade, politicians have responded by forging a distinctive programme of English devolution focused on city-regions. In this article, we analyse the core drivers of the English devolution agenda to understand its impact on the future trajectory of British politics. We identify the predominance of a narrow economic vision of devolution that systematically negates other agendas. The result is a failure to address the trade-offs inherent in the devolution process, alongside an inadequate engagement with the growing demand for democratic revitalisation. In the long-term, we argue that the empowerment of the largest cities in England and the relative neglect of non-urban areas will exacerbate power asymmetries within the UK political system in both centre-periphery and centre-local relations, a phenomenon we term ‘political spatial inequality’. There is a risk of resurgent ‘territorially based populism’ stemming from this uneven political geography which has the potential to exacerbate political instability and significantly reshape UK politics in the wake of Brexit. English devolution is a prescient example of how policy ‘solutions’ can in turn create new problems that pose major challenges for policymakers.