Harry was not a fan of "functions". He might have found it novel the first couple of times, but he'd been to entirely too many. He hated dressing up, so he refused to wear a tie just to be contrary. If anyone dared kick him out, maybe he could get out of being invited to the next one.
At least the food was free. He wondered if Ron or Hermione were in attendance, or really anyone he knew. If he didn't latch onto someone early enough, he'd be drawn into conversation by every political social climber there. It wasn't as bad as it had been the first few years after the war, but there were still people who wanted a photo with 'Harry Potter' (tm). He got himself a proper drink at the bar and started a to make his way around the room, trying to look like he was going somewhere purposefully until he found a friendly face.