Assume a child (aged 15) has a different surname to its mother. They live with their mother and father, but the mother did not take the father's name on marriage. All three are UK citizens, have UK passports in their own name, are UK resident, and the father and mother are married. The only thing mildly unusual (and hardly remarkable in the 21st century) is the mother did not take the surname of the father on marriage, and the child has the surname of the father (which is different to the mother).
A few of weeks ago, the mother and child travelled by plane to an EU destination, without the father.
On flying out of the UK, this presented no problem.
On returning to the UK (from the EU), a long dialog with the immigration officer ensued where he threatened to not permit re-entry because the child had a different surname to the parent traveling, and "The Children's Act" (sic - there are several) requires that the child also carries a birth certificate. Eventually (30 minutes later, and after interrogation as to what the child's middle names are etc), common sense prevails.
There were no other factors likely to interest the immigration officer. The child's passport had been issued a month previously and the photograph was thus a good likeness. The child concerned had no difficulty travelling with school to another EU country without a birth certificate or any letters from either parent.
This seems completely bizarre to me, given:
I can find no legal requirement that anyone needs to carry a birth certificate.
The child could simply have gained entry as a UK citizen if the mother was not there at all.
The risk one would have thought needed addressing was one parent absconding with a child after separation. In this case, should the check not be being made on departure? Return to where all parties are resident seems unproblematic.
The fact mother and child have different surnames is not indicative of marital break-up (consider e.g. unmarried parents); indeed when a married couple break up it is likely (if they changed name on marriage) they will still have the same surname (at least on their passport) for a while.
So, to my questions:
Is there a requirement that children traveling with a parent with a different surname carry their birth certificate?
If so where is the legal origin of such a requirement?
Note: I am not asking this in order assist in the parent concerned raising a complaint against a particular immigration officer. I am asking so I can tell the parent concerned what the requirements are should she wish to travel with her children unimpeded in future.