Originally Posted by
ahmetdouas
I don't know if it is the law in the UK, pretty sure it is in the US though, as in US citizens MUST use their US passports when exiting and entering the US.
This famously happened to Boris Johnson a while back. He was born in New York so was a US citizen (no longer). He was denied boarding going to Mexico for a family holiday via Houston because he didn't have a valid US passport. He ended up rerouting so he didn't go through the US.