Originally Posted by LondonAussie

I had this happen once returning EU to UK and had to check-in with an agent. After swiping my Australian passport, he asked how long I was intending to stay in the UK for, and when I said indefinitely he asked about my residency status. He starting flipping through my passport, I assume looking for a residency permit / visa, but it's rather full of stamps and he seemed to give up after a few pages and then said quite curtly - you can stay in the UK for 6 months, and handed it back to me with my boarding pass. Was quite unusual and thankfully hasn't happened again since.