The first time I went to the Warner Brothers Harry Potter Studio Tour was in 2015, just after they had added the Hogwarts Express and Kings Cross set to the tour. At the end of November 2019 we made a return visit, mainly to see how different it was dressed for Christmas and with snow.
I had seen the Yule Ball set before, but that time it was in the main part of the tour, this time it was placed at the end of the Great Hall.