
I asked for permission to take her apart, learning that the "skirt" piece was actually the torso from an old fig. I promptly ran off to the Brick Bazaar, where by a stroke of luck Bob Kojima was selling these old figs for 50 cents each. I picked up a pair of them (anyone know what set or theme these are from?):

Taking a break from sorting this weekend, I tried to recreate this minifig design, but couldn't figure it out, so I came up with something similar of my own:

To create a long-skirted castle minifig of your own:
1. Take the head off an old fig with a 2x2 base and no arms.
2. Insert a Technic axle pin into an axle joiner.
3. Put the axle pin and joiner inside the old fig's body and thread the pin through the head-hole.
4. Insert the Technic pin into the minifig torso.
Note: The Technic pin will only fit into an old-style minifig torso. The new-style torsos have flanges (or something) that prevent it from fitting.
Unfortunately, my camera's battery was dead by the point when I saw this in the display, so I didn't get a closeup picture of the black farmer's hut the lady was standing next to. If you know whose design this is, please speak up!