In R.S. Hawker's short story "The Botathen Ghost," there is a comment that a Cornish clergyman "must needs have been artist and poet in his way, for he had to enliven his people three or four times a-year, by mastering the arrangements of a 'guary', or religious mystery, which was duly performed in the topmost hollow of a green barrow or hill, of which many survive, scooped out into vast amphitheatres and surrounded by benches of turf which held two thousand spectators."
This is a reference to the famous Cornish Rounds, huge earthworks which medieval actors used to stage religious plays. In the Cornish tongue, such an outdoor theatre was known as a "plen-an-gwary" or playing place. There are traces of as many as 18 of these rounds, though only a couple are still visible. The famous Perran Round, however, shows evidence of seven tiers of seating and could have accommodated an impressive audience for medieval plays.
In "The Botathen Ghost," Hawker notes that some of those plays included "'The Creation' and 'Noe's Flood', which still exist in the original Celtic as well as the English text." There is in fact an extensive cycle of Cornish mystery plays known as the Ordinalia. The first section of the Ordinalia tells the stories of the Creation, the Fall of Man, Cain and Abel, Noah, and Abraham.
Hawker's story goes on to grant a parson who organized such plays the power to "govern any ghost or evil spirit." I'm not sure about that, but the plays must have required a steady hand to organize them all. The cycles performed in Cornwall seem to have lasted several days. They told the story of the world from the Creation to the Ascension, though unlike the extant mystery cycles in Middle English, the Ordinalia leaves out the Last Judgment.
By the way, Hawker seems to imply that the Rounds were built to be theatres. Most scholars today believe they were constructed for other purposes, but they were no doubt utilized by medieval players. As to whether or not they are haunted... I defer to Mr. Hawker on that one!
