Official data from the Department for Work and Pensions' Family Resources Survey reveals that 12% of UK children - approximately 1.7 million - are now reported by their parents as living with a long-term illness, disability or impairment. This figure has nearly doubled from 7% in 2014-2015, with the proportion remaining stable between 2023-2024 and 2024-2025. Among disabled children, social or behavioural issues are the most common category, affecting 61%, followed by learning impairments (32%) and mental health conditions (26%). Parallel trends show sharp increases in autism and ADHD diagnoses, with NHS data indicating the proportion of 16-24 year olds reporting autism rising from 5.4% in 2022 to 8.9% in 2025. The government has launched an independent review into rising demand for mental health, ADHD and autism services to identify underlying drivers. This surge coincides with quadrupled Disability Living Allowance claims for behavioural disorders since before the pandemic, including thousands of claims for very young children. While greater awareness and diagnostic changes play a role, the scale prompts questions about environmental factors, policy impacts on child development, and potential over-medicalisation that echo historical inquiries into population health like the 1904 Fitzroy Report. Without deeper investigation into root causes beyond benefits system tweaks, the UK risks long-term societal and economic consequences from a generation facing unprecedented barriers to education, employment and military fitness.