“”This child is British by birth and South African by descent.””
The parents live in Britain. No mention as to what, if any, passport the parents carried. The parents are civil servants in Britain.
It is the grandparents who are South Africans.
I can understand why USA turned down a visa request for the kid.
Since kid was born in Britain and lives in Britain, just maybe they ought to turn in the South African passport and get the kid a British passport and then they can take the kid throughout the world on a tourist visa.
They probably reasoned that it would be suspicious to be traveling with a child with a different passport. My wife got the third degree from immigration in Australia in the early 90's traveling on her Canadian passport issued in her maiden name with our two children who had US passports.