do i need to carry old passport

[neilroy]

No w since i have acquired the red passport do i still need to carry old passport everytime i go to differnt country as proof of my old citizenship?

[eliasuk4u]

since i have acquired the red passport

Can u be more specific. What do you mean RED passport? Do you mean British Passport???

[Christophe]

Assuming a 'red passport' is a British passport (I always thought they were maroon, but still...), then the short answer is, no, you need to carry only one passport.

Beyond that, it is difficult to answer your question without knowing whether you are still a citizen of your 'old' country. If you are (i.e. you did not renounce or automatically lose that citizenship on becoming British), then you can of course continue to use the old passport, since it remains a valid document. You should use your British passport to enter and leave the UK (although there is no absolute legal requirement to do that, but it's obviously much more straightforward if you do), but outside the UK you can travel on another passport if you want to.

If you are no longer a citizen of your original country, then of course the passport is no longer valid as a travel document and you ought not travel on it. If you have any visas in that passport, you will need to get new visas in your British passport, if visas are needed for British citizens.

It is conceivable that some countries might have your details on a database, either fingerprints/eye scans (as in the US) or simply personal details such as date and place of birth and so on. Therefore, I suppose that you might be asked, on entering such a country, why you are now travelling on a different passport from the one you used before: if so, a simple statement that you have been naturalised as a British citizen ought to suffice: after all there is nothing unusual about that. You could carry your old passport with you, but it shouldn't be necessary to do so.

[tekaweni]

Some countries (like South Africa) require dual-nationals to use their 'local' passport for entry into that country.

As far as I'm aware this only ever applies when entering your original country, not any other.

Britain does not care which passport you travel on, so long as it's valid.

[Christophe]

Britain does not care which passport you travel on, so long as it's valid.

And, if entering the UK, so long as it is valid for the intended purpose of the trip. (So, e.g. a dual national of the UK and South Africa could enter the UK on an unendorsed South African passport as a short-term visitor, but not if the intention was to live in the UK.)

[Dawie]

Britain does not care which passport you travel on, so long as it's valid.

And, if entering the UK, so long as it is valid for the intended purpose of the trip. (So, e.g. a dual national of the UK and South Africa could enter the UK on an unendorsed South African passport as a short-term visitor, but not if the intention was to live in the UK.)

It's an interesting point whether or not a UK citizen may be granted limited leave to enter the UK on an unendorsed foreign passport. Just because you do not have your UK passport to hand does not change the fact that you are a UK citizen and therefore are totally free of immigration control.

I'm sure that if you were to present an unendorsed South African passport for entry at a UK port and then declared that you were also a UK citizen they would be obliged to follow that up. Of course that could involve a lengthy wait at immigration while they check your details, but it would certainly be possible for them to contact the Nationality Directorate and find out if anyone matching your details is listed on their records as a British citizen.