If a UK citizen answers the application questions honestly they will not receive an ETA. It clearly asks if you a dual citizen and rejects it if you claim UK nationality. Believe me, I tried when applying for my wife.
There was a short period of time leading up to the February 25th deadline where it was possible for dual citizens to legitimately receive an ETA despite their British citizenship.
I think it was specifically introduced to give those people without a uk passport the time to apply for and receive one before the new rules came into force and still be allowed to travel into the UK.
I have completed application for ETAs for 3 persons literally few minutes ago. They ask you for all your nationalities on one of the steps in the application process.
Let’s rememember there are some hundreds of thousands of flights either into or out of Schengen airports each month. One bad experience is not vey indicative of what is happening with the new procedures.
Well she says she is British - but also says she isn’t because her father wasn’t able to pass it on to her. Seems more of a case that she’s not even got official status in the UK rather than a dual citizenship problem.
I don’t understand why she can’t just get an ETA for her Spanish passport since as things stand at the moment she’s not actually a dual nationality citizen.
Blows my mind that you’d live in the UK your whole life without sorting out your official status in some way. She might have bigger problems getting back than she thinks.
I’ll travel abroad. What should I pack? My passport or my dad’s birth certificate? ![]()

Passport or ID for domestic/ inter-Schengen. Passport for all other flights.
She may not have taken them along - maybe her dad texted her whatever docs he could think of in order to strengthen her case.
Still, as has been pointed out, to live all your life in a country with what’s tantamount to no legal status when you could easily have applied for it is just dumb. Especially in this day and age.
E-mailed Dover Port to check what we should do as we have Swiss residence permits so are exempt from the EES thing. They replied that it’s not yet running for tourist traffic due to problem with the French technology side of things.