Concept Art: The Lady of the Green Kirtle’s Lair
It is generally known that The Lady of the Green Kirtle appeared in early versions of the screenplay for The Voyage of the Dawn Treader.
Below is a piece of concept art that NarniaFans came across on Federico D’Alessandro’s website. It appears to show the Lady of the Green Kirtle’s throne room. As for the Lady herself, my guess is they just threw an image of the White Witch in there as a temporary placeholder. Caspian is clearly a placeholder because he is wearing exactly the same armor he wore in Prince Caspian.