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Hi thank you for your message, was his birth registered in the UK?
Hi thank you for your message, then he is a British citizen. He could just apply for a passport for example. You can also see more information concerning this here: https://www.gov.uk/check-british-citizenship/born-in-the-uk-between-1-january-1983-and-1-october-2000
Hi thank you for your message, yes, you can find records for all births registered since 1837 at the national archives here: https://www.nationalarchives.gov.uk/help-with-your-research/research-guides/birth-marriage-death-england-and-wales/