Adapted from British Goblins - Welsh Folk-lore, Fairy Mythology, Legends and Traditions by Wirt Sikes.
ON A CERTAIN FARM IN GLAMORGANSHIRE lived Rowli Pugh, who was known far and wide for his evil luck. Nothing prospered that he turned his hand to; his crops proved poor, though his neighbours’ might be good; his roof leaked in spite of all his mending; his walls remained damp when everyone else’s walls were dry; and above all, his wife was so feeble she could do no work. His fortunes at last seemed so hard that he resolved to sell out and clear out, no matter at what loss, and try to better himself in another country.
So as Rowli was sitting on his wall one day, hard by his cottage, musing over his sad lot, he was accosted by a little man who asked him what the matter was. Rowli looked around in surprise, but before he could answer the ellyll said to him with a grin, “There, there, hold your tongue, I know more about you than you ever dreamed of knowing. You’re in trouble, and you’re going away. But you may stay, now I’ve spoken to you. Only bid your good wife leave the candle burning when she goes to bed and say no more about it.”
With this the ellyll kicked up his heels and disappeared. Of course, the farmer did as he was bid, and from that day he prospered. Every night Catti Jones, his wife, set the candle out, swept the hearth, and went to bed; and every night the fairies would come and do her baking and brewing, her washing and mending, sometimes even furnishing their own tools and materials. The farmer was now always clean of linen and whole of garb; he had good bread and good beer; he felt like a new man and worked like one.
Everything prospered with him now as nothing had before. His crops were good, his barns were tidy, his cattle were sleek, his pigs the fattest in the parish. So, things went on for three years. One night Catti Jones took it into her head that she must have a peep at the fair family who did her work for her; and curiosity conquering prudence, she arose while Rowli Pugh lay snoring, and peeped through a crack in the door.
There they were, a jolly company of ellyllon, working away like mad, and laughing and dancing as madly as they worked. Catti was so amused that in spite of herself she fell to laughing too; and at sound of her voice the ellyllon scattered like mist before the wind, leaving the room empty. They never came back any more; but the farmer was now prosperous, and his bad luck never returned to plague him.