Brextinction? How cohort replacement has transformed support for Brexit

Abstract Public support for Brexit has declined since the 2016 referendum. We argue that part of this decline is due to cohort replacement where many older voters (who support Brexit) have passed away, while younger voters (who oppose Brexit) have entered the electorate. Using a series of original YouGov surveys from 2016, 2018, 2020 and 2022, each representative of the UK electorate, we first demonstrate the large and stable differences in Brexit support between younger and older voters. Next, we employ demographic decomposition calculations to estimate that cohort replacement alone accounts for approximately one third of the decline in aggregate Brexit support in just 6 years (with two thirds of the decline being explained by within‐cohort changes). Furthermore, by combining our data on Brexit support with Office for National Statistics cohort projections up to 2030, we derive testable hypotheses about the pressure that cohort replacement will continue to put on Brexit support over the next decade across a wide range of potential scenarios. Altogether, our study demonstrates the powerful role that cohort replacement plays in shaping British (and European) politics in the post‐Brexit world.