1986 British Born, Have Birth Certificate, Unmarried Parents

I have my English birth certificate, both my English father and US mother are on it. They were un-married.

Why do they stipulate pre-1983 as OK and post-1983 as a legacy-eligibility only (cannot pass onto my son).

So confusing. See supportive document taken from


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Documentary evidence that (had the law been different) you would have become a British citizen:

Send the following documents:

 Your passport (got it)
 Your full birth certificate and either: (got it)
 Your father's full birth certificate (don't have it, don't know him)
 His certificate of naturalisation or registration as a British citizen or as a
citizen of the United Kingdom and Colonies (or, before 1 January 1949, as
a British subject)
 Papers showing his legal adoption
 His expired citizen of the United Kingdom and Colonies passport
 Evidence that he was settled in the UK at the time of your birth, if you were
born in the UK on or after 1 January 1983.

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The citizenship you will acquire:

If you would have become a British citizen by descent had your parents been married, you will be a British citizen by descent after registration under this provision. British citizens by descent cannot normally pass on British citizenship to any children born outside British territory.

If you are resident in the United Kingdom, and 18 or over, you may therefore wish to consider applying for naturalisation, as that would give British citizenship otherwise than by descent which would allow you to be able to pass on that citizenship to any children born abroad to you in the future.