In keeping with the 35 Years of Magic theme, you may wish to add to the festivities by dressing up in a 'Magic' theme. The Christ's College Dining Hall looks just like the "Hogwarts" dining hall.
Costume ideas can be as simple as wearing a witches hat, or Harry Potter themed item, or a wizard robe. You may like to go full-on and come along as Dumbledore, or keep it low-key and subtle and carry a wand? Maybe you have a Magician's top hat?
Dressing up is NOT compulsory, it's just for fun.