Not exactly waiting for a gate, but:

On AMS-LHR on BD a few weeks ago they announced that our gate was occupied. Without any warning, they just pulled up to the terminal and unloaded through steps. I (and many other) passengers thought that we would have a jetbridge, only to step out onto a stairway directly to the tarmac. Fortunately it was only a short walk from Arrivals.

This Saturday, BA875 DME-LHR pulled up to a domestic UK arrivals gate. They then unloaded through stairs at the rear door (i.e., CE passengers last), and then took us on a 10 minute bus tour of LHR over to T1 International Arrivals.