This lecture will reflect on changes in UK energy policy since the early 2000s, when the first long term emissions target was proposed in the 2003 Energy White Paper. The UK is already well on the way to meeting that target, which required a 60% reduction in greenhouse gases by 2050. In the meantime, many changes have affected the energy sector: climate science has highlighted the need for more urgency and ambition; technologies that were previously expensive have fallen in cost; politics at home and abroad are subject to increasing uncertainty and turmoil – including the UK’s relationship with Europe and the rest of the world. Despite progress with reducing emissions, there is still a long way to go to meet the new target of a net zero energy system and economy by 2050. The lecture will discuss some of the successful policies that have driven emissions reductions so far, mainly in electricity. It will also highlight the range of difficult challenges policy makers will need to address if the net zero target is to be met