The years immediately after the 2015 general election were dominated by another vote, held in 2016. In 2013, the electoral challenge from UKIP had forced David Cameron to promise an in–out referendum on the EU should his party win the next general election. Cameron fulfilled his promise, after negotiations with the EU which only partially addressed the grievances of Eurosceptics in UKIP and within his own party. The chapter discusses the narrow victory for ‘Leave’ in the 2016 referendum, arising from divisions within the UK which cut across previous party allegiances and introduced a new element of volatility in an electorate which was already barely recognizable from that of 1964. The situation was complicated further by the election of the radical left-wing MP Jeremy Corbyn as Labour leader after his party’s 2015 defeat. By contrast, when David Cameron resigned as Conservative leader and Prime Minister after the referendum he was succeeded by Theresa May, who was regarded as a pragmatic centre-right politician who could negotiate a compromise ‘Brexit’ deal with the EU. The chapter examines May’s failure to carry out this promise, marked in particular by her inept attempt to secure a convincing parliamentary majority in the 2017 general election. When May was forced from office in 2019 she was succeeded by Boris Johnson, a far more controversial and divisive character who nevertheless was able to lead the Conservatives to a comfortable electoral victory, not least because their pro-European opponents were hopelessly divided. However, the victorious Conservatives had no reason to feel complacent; even if Johnson’s government could deliver the favourable Brexit deal which it had promised, over the years since 1964 the British electorate had become far more fickle and parties were increasingly vulnerable to events outside their control. Within a few months of the 2019 election, party competition in Britain, which had seemed so stable back in 1964, was exposed to a new and deadly source of disturbance—the outbreak in China of the Covid-19 virus—which presented the most serious challenge faced by any UK government since 1945.