What primarily drove the great decline in mortality in industrializing Britain: rising nutrition and living standards, or public health measures such as sanitation, clean water and vaccination?

Thomas McKeown's 1976 analysis credited the mortality decline mainly to better nutrition, with hygiene and medicine playing later, smaller roles. Demographers disputed this from the moment it was published, and historians such as Simon Szreter later argued McKeown understated public health infrastructure, including water supply, sewage systems, housing improvement and vaccination. The balance of causes remains debated rather than settled.