On a small promontory jutting into St Tredwell’s Loch from the east, is a confusion of ruined buildings. At the core of the mound is an Iron Age fortification, but the rectangular walls on the top are those of a medieval chapel. St Tredwell is mentioned in a late medieval account of the mission that King Nechtan invited to Pictland: its leader was Boniface and Triduana or Tredwell was one of the “holy virgins” who accompanied him. Legend recounts that Nechtan fell in love with Triduana and praised the beauty of her eyes. She responded by plucking them out and sending them to him skewered on a thorn.
St Tredwell was widely venerated in Scotland and the lochs and wells associated with her were famous for curing diseases of the eyes. Pilgrims travelled to Papay from all over Orkney and the north seeking cures at St Tredwell’s loch, and were still doing so long after the Reformation