It was 2011. It was the Reeperbahn Festival in Hamburg. There was a mic echo that could have been made to order for Sheeran's slow, slightly mournful "Hallelujah." His natural, slight rasp helped, too.
He kept it simple, save one attempt at the end to go full Buckley with a dramatically drawn-out note. Sheeran didn't quite make it, his voice breaking, but it's part of the charm because, well, it's Ed Sheeran.