Post
by marcnath » Tue May 01, 2018 11:20 am
The key thing is to be sure on what basis the entry back into UK is. So, if the immigration officer stamps him in as a visitor (end date for visa), then the ILR will get invalidated.
Upon entry into the UK, only one type of entry can be valid. So, to make sure ILR remains valid, one always has to enter as a Returning Resident, not as a visa waiver visitor or any other category.
I have no idea if the officer will accept the BRP card with the US passport and admit him as a returning resident, but I would guess he would. But not sure if it is a risk I would take. Of course, there is the worst case option of leaving the UK from the airport if the officer does not agree and come in once he has the Australian passport.
My comments are in no way meant to be advisory. I have no professional knowledge of immigration. These are based on my own experience, convictions and personal interpretation of publicly available information.