Once upon a time, I was president of CUHaGS, which has quite a large crossover with the Monarchist League. CUHaGS has a tradition that the annual dinner is held at the college of the president, so in my year it was held at Sidney.
People often get up and walk around outside between courses, so that they're sitting next to someone else for the next course. (I don't know whether that's just a Sidney thing.) And I began to overhear Monarchists saying things to one another like "I've just been for a leap", or "I fancy a leap. Want to come?"
Some background here. Despite being 400 years old, Sidney has produced approximately two famous people: Carol Voderman and Oliver Cromwell. Cromwell, as you probably know, killed King Charles I. At the restoration of the monarchy, Charles II had Cromwell's body dug up and hanged, and his head put on a spike. Then someone stole the head.
Centuries later, that person's descendant decided it was a bit creepy having a head around, and gave it to Sidney. The head was buried in the chapel, but its exact location remains a secret known only to the Master and a few Fellows. Otherwise there was a risk that monarchists would dig it up again and use it as a football.
Anyway, I investigated what the people going for a "leap" were up to. Of course the Monarchists hate Cromwell, because he killed a king. It turned out that they often hold dinners at Sidney, get drunk, and go to the chapel, and jump up and down on random parts of the floor in the hope that they're showing disrespect to Oliver Cromwell's head.