Similar at Gatwick the weekend before last. Arrived at around 0200 onto an airbridge, but there was no-one to open the door at the top of the airbridge into the terminal.
The guy who positioned the jetway wasn't allowed to - it has to be a BA host who does that job. Similar from the crew - whilst they could open the door, processes meant they had to wait for a BA host to open it. As we were an hour late, there was no BA host. We waited for 30 minutes on the airbridge while responsibility between those who remained was agreed.