Experts thought it was an unknown chamber
Exeter Cathedral revealed yesterday afternoon (Tuesday 12th February) that it had made an "exciting new discovery".
They took to Facebook to break the news saying they'd found: "a hole leading to a previously unknown chamber in the Southern side of the Cathedral. The Masons are currently reviewing a 3D scan of the room, and we'll have more info for you soon. . ."
They then updated the page last night to say it was actually "less exciting" and was in fact a small void leading to the drainage system. They ended the post saying "Whoops!!"