Better late than never!

[LizzieW]

Perhaps the 21 year old wanted to get married, had always been known by her father's name and just wanted it to be correct to show her husband to be - or maybe her future in laws.  Remember parents even in the 1960s had a lot of control over their children.  My f.i.l even wanted to see our bank accounts to make sure we weren't spending too much!

[andrewalston]

Could be. The child married in Q3 of the following year.

[Jebber]

My understand is that someone over the age of 21 cannot be adopted, so presumably it took place before her 21st birthday.

Hopefully AnthonyMMM or StanMapstone  will come up with an explanation.

[AntonyMMM]

One I have yet to work out is an adoption of a child in 1967. The child was bon in 1946, and the parents married in 1947. Why adopt someone aged 21?

Assuming you have seen a certificate from the original birth registration, the mother is named, but no father, and it is annotated as "adopted" in the margin ? If so, then normally you would  assume that the father wasn't the child's biological parent, and so the child was adopted to legalise the step-relationship  - probably for inheritance reasons. As mentioned it had to be done before the child was 21 (18 today).

If both were the natural parents it should have been a simple re-registration under the Legitimacy Act - but there were circumstances when that couldn't happen, so there may be another explanation (if they were the real parents).

If one (or both) wasn't free to marry when the child was born i.e. they were married to someone else, then the Legitimacy Act 1926 couldn't be used - and I think the adoption could be a way of legitimising the child and getting around that (but I would want to investigate further to be sure).

That restriction, which was designed to ensure that children of "adulterous relationships" could never be made legitimate under the Act, was removed under a new Legitimacy Act in 1959.

[andrewalston]

No, I haven't seen the certificates.

The birth was in Germany, and the marriage is in the UK "Overseas" lists as being an Army marriage in Hamburg, so father was almost certainly part of the occupying forces.

So, I have the mother's maiden name from the marriage and subsequent UK-born children. Because the overseas index and the adoption index only give the year, it is possible that the child was just under 21 at adoption.

It's part of my one-name study, and as it relates to living people, I don't want to pry too hard. 

[AntonyMMM]

If the birth/marriage took place outside the UK, then that would also be a reason for the Legitimacy Act provisions for re-registration to not apply - but, as always, without seeing the actual records, you are working on assumptions & guesswork only.