It was one day in his cell on Glastonbury Tor that he was invited by two ‘demons’ to speak with Gwyn ab Nudd, King of Annwn, on the top of the hill. On reaching the top, he saw the fairest castle that he had ever beheld, manned by the best-appointed troops; and there were musicians, steeds, maidens and every magnificence becoming the court of a sumptuous king.
He beheld a courteous man on the rampart, who bade him enter, saying that the king was waiting for him to come to dine.
Collen entered the castle, and found the king sitting in a chair of gold. He welcomed Collen with due honour, and bade him seat himself at the table. ‘Hast thou ever seen men better apparelled than these in red and blue ?’ asked the king.
Then answered Collen : ‘ The red on the one side betokens burning, and the blue on the other betokens cold ‘; and with that he drew out his sprinkler and dashed the holy water over them, whereupon they vanished out of his sight. ’
Many later tellings of this myth say that it happened in the Berwyn Mountains to the south of Llangollen. However, the Buchedd Collen clearly states that it occurred whilst Collen was in his cell on Glastonbury Tor, before he journeyed to Llangollen.
