Dahl's Chickens

Farmer Dahl has been struggling of late because of Farmer Barry O'Vine's efficient, productive and very cramped new farm. If he doesn't come up with a solution, he will have to sell up and probably retire. Farmer Paul Tree, who runs a chicken farm, arrives back from Fawgull Island carrying a strange colourful hen under his arm. He gives the hen to Farmer Dahl and states that the hen can speak, read thoughts, and is very special .. but how special?