It happened during renovations at St. Mary at Lambeth.
… Lifting the flagstones (to an entranceway), contractors found the entrance to a passageway with a staircase going down into the darkness. They attached a cellphone to a long stick and filmed the brick-lined vault. They were shocked to discover it was crammed from floor to ceiling with lead coffins, 30 of them. One of the coffins, they noted, had a red and gold pointed hat perched upon it, the mitre of an Archbishop.
There, they found not one, but five missing archbishops!
Hmmm … I was not aware that they had gone missing!