Any experience of childhood poverty affects life chances, but longer exposure is particularly detrimental to education, health, and future earnings. This study examines trends in long-term childhood poverty in Britain. Using a life-course perspective, we tracked poverty from birth to age ten among 1991–2017 birth cohorts. Our findings show that, on average, 17 per cent of children spent at least half of their childhood in poverty. Long-term poverty affected 25 per cent of those born in the early 1990s, markedly declined to 13–14 percent for cohorts born after the post-1997 welfare reforms, and rose again to 23 per cent for children born following the 2013 austerity reforms. These trends are driven by shifts in the penalties associated with work-family risk factors, rather than by changes in their prevalence. These shifts in penalties reflect broader changes in redistribution and predistribution. The decline in the 1990s was largely due to rising employment and earnings in low-income households, whereas the post-austerity surge stems from reduced redistribution. For cohorts born in the 2000s, social transfers played a substantial role in containing long-term poverty despite worsening predistribution. Overall, the findings show that long-term childhood poverty is a major challenge in Britain and highlight the need to strengthen redistribution and predistribution