This paper argues that the rise in populism and the imperative to leave the EU (‘Brexit’) can be traced to generational shifts away from party attachment. It uses longitudinal data from the British Household Panel Survey/Understanding Society to track a tendency in people to become less attached to mainstream political parties over the past three decades. We argue that this individual level data is superior to cross sectional snapshots of party attachment because it captures the shifting dynamics of individual trajectories of party support. These dynamics are theorised in terms of a deep rejection of the centre-ground in favour of a ‘melancholy politics’: acts of nationalist sentiment driven by a mixture of pessimism about the future, nostalgia for the past, and a pervasive sense of the irreversible decline concerning the present. The paper concludes that these cohort changes signal to political parties the need to develop policies which more clearly differentiate their ideological positions, without which the ‘enemy’ will continue to be misidentified.