A story about the fairy kingdom in Ireland is found in the Theosophy book, "The Lives of Alcyone" by Annie Besant and C.W. Leadbeater. In it they track 48 past lives of Alcyone. This chapter is about his 13th life on Atlantis around 27,000 B.C. However, in this same chapter, we are following the story of a young girl named Yajna who finds an enchanted cave in Ireland:
The young girl "... told a strange tale. When wandering on the hill, quite near her own home, she had come upon a little hollow in the hillside which she had never seen before, and had found in it the entrance to a cave. She had hesitated whether to go farther, because of the darkness; but while she stood looking, a handsome boy came out of the cave, and with a deep bow invited her to enter.
"She was flattered by the deference with which he seemed to regard her, and asked him who he was, and where he lived. He replied that the cave was the entrance to his home, and that he would gladly show her the beautiful gardens which were but a little way within.
"She wondered much, but curiosity triumphed, and she put her hand trustingly in that of her guide, and let him lead her into the darkness. He seemed to be able to see quite well, and led her unhesitatingly forward; and after walking for a few minutes they came, quite suddenly and round a corner, upon a hall so vast that it was as though they were again in the open air.
"Yajna had no recollection of seeing the sky, but had the impression of a pleasant warm light like sunlight. They seemed to be in a garden, full of the loveliest flowers and trees, yet none of the flowers or trees were exactly like any which she had ever seen before.
"The boy led her forward through the garden, and presently they came upon a number of other children, who seemed to be playing some sort of game, in which both she and her guide joined; but she was never able to explain quite what the game was, except that it was not like any played on earth. The merry party played and danced for hours without the slightest feeling of fatigue, and varied their proceedings by wandering hand in hand among the gorgeous vegetation, and on one occasion plunging into a crystal lake and splashing about in deliciously warm water.
"Yajna was deliriously happy, and earnestly wished that her brothers and sisters and friends could share her enjoyment; indeed, she asked her boy friend whether she might come again and bring them all with her. He laughed joyously, and said that they would be heartily welcome if they could find the way—a cryptic utterance which Yajna did not understand, but she asked no more, lest she should seem rude.
"Nevertheless, in the midst of all her play curious little twinges of longing for her mother obtruded themselves into her mind—doubtless the result of the anxious thoughts of Mercury while the search was going on. [Her father was looking for her].
"Suddenly there came to them through the garden a shining form to whom the playing children paid great deference; he spoke earnestly to the boy who had befriended Yajna, and then passed rapidly away. The boy called to Yajna, and told her that her father wanted her, and that he would take her to him. She ran to him at once, and he led her away from the garden, and up a curious stairway, which led them out among the roots of a great tree, and so into the old familiar world of daily life.
But somehow that world seemed strangely dull, and the very sunlight itself looked pale after the golden light of the cave. The boy asked her to sit down beside him on the ground, and when she did so, he put his hands upon her shoulders and looked long into her eyes. His gaze was kind though compelling, and under it she found herself sinking into sleep. Her last remembrance was that he stooped forward and kissed her as she sank to rest, and after that she knew no more until her father's touch awoke her."
Yajna tried several times to find the cave. It was all in vain. She never did. The story of fairies in the Emerald Isle is an ancient one. We wouldn't be surprised if this little purple guy frequents that cave.