Thank you so much for your reply! I don't know what ECO means but I assume it is the customs officer at the border right? I understand now. So it means nothing is wrong with me going in and out of the UK on another passport but I must make sure when I come back to the UK that the officer puts me as ...

This is from the document that was kindly posted above, page 22 "You must not treat an application as withdrawn if the person: •does not request the return of their passport and instead travels outside the CTA on another passport , an emergency travel document or illegally •requests the return of th...

Also, my pre-existing visa will still be valid

My other passport allows me to visit the UK without a visa (Antigua and Barbuda)

Dear all,

Is it legally possible to travel outside the UK on another passport whilst making a 'Leave to remain' application for a general Tier 4 visa from within the UK?