The Office for National Statistics compiles annual (mid-year) population estimates for England and Wales based on the latest Census of Population, with allowance for under-enumeration, and updated to reflect subsequent births, deaths, migration and ageing.

Estimates of the national population are available by sex and single year of age, with corresponding data at standard region, county, local authority district/London borough, health region and health district levels.

This national series began in 1900 (with varying degrees of age/sex disaggregation) and sub-national estimates are available from 1971. Data are published annually about twelve months after the mid-year reference date.

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