I'm a bit lost about your scenario ... If there's a specific country this relates to please let us know which country it is.
This is how it works in the countries I know:
- If country passport expires the citizenship associated with that passport doesn't expire, therefore you are still a dual citizen.
- In your origin country you count as a citizen of that country, not as a British citizen, even if you enter with a British passport.
- the British government advises dual citizens that they generally cannot expect consular support in their origin countries.
- You are free to enter your origin country with their passport.
- And you are free to use the British passport to enter the UK (otherwise questions will be asked at the UK border.
so is using two passports in such a way (use CoO when visiting CoO and then of course British Passport when coming back to UK) still acceptable?
This has always been acceptable (not sure why it should have changed?).