My grandma got really ill, and we got an emergency flight (like a couple of days notice) I was the only child at the time, so there's no "Oh, but what happens to x" etc..
I flew out, I guess without the normal procedures because I was just under the age of one ie: ordinarily there'd be no need for me to have a passport
When we came back, the authorities wouldn't let me in, because their reasoning was "This is not a British baby. You're smuggling a Pakistani born kid"
It didn't help that I apparently walked and talked, and basically clinged to all the old ladies in Pakistan, and apparently I wanted to sleep with "bay", despite her being ill
so the authorities wouldn't really believe my parents.
It took about 6 months and me having an episode (with my grand dad and great uncle shouting like hell at my parents for taking me there - got a little back story for that, but a sad one
), to get all sorts of documents from the UK to Islamabad.
They finally accepted a birth certificate after about 6 months!