A person's official date of birth may be obtained online via the links on The National Archives website. A few basic details are required to begin. These include the person's name, the likely district of their birth and the approximate date of their birth.
Providers of information include the General Register Office and the government, and often there will be a fee for making requests. Reliable indexes date back to July 1, 1837, when civil registration began. Earlier records can be found in the parish registers of local archives.
Other possible sources of information include websites such as FamilySearch, Ancestry, Findmypast and Deceased Online, all of which charge fees.