Originally Posted by
bthere79
i know several UK/EU dual nationals who only ever travel on one passport only without any issues
i usually use my respective ID at passport control but i never -ever- bothered to update API details between outbound and inbound and i've never had any issues whatsoever
i think you might be overthinking it slightly
Do they travel with the UK passport only? That I could believe -- since ETIAS is not yet in place, in theory I could take my UK passport to Poland and use it there and get away with it (it's not officially allowed under Polish Law but I don't think they currently have a way of checking). Once ETIAS is in place, then you still will be able to but they'd need to apply for an ETIAS in the UK passport (it remains to be seen whether that will be allowed for dual nationals).
Regarding flying back to the UK with an EU passport as a dual national, I don't believe that's possible with the ETA system in effect. A Dual National cannot legally apply for an ETA. Here's some interesting information on the subject
https://commonslibrary.parliament.uk...ngs/cbp-10344/
-simon
https://commonslibrary.parliament.uk...ngs/cbp-10344/