Remove ham from roaster. Cut away and discard tough outer skin.
Brown mushrooms in butter. Cut a slash in the top of the ham sufficiently large to hold the mushroom mixture, water, salt and pepper. Skewer the opening to keep the filling in place.
Make a sauce of the 2 tablespoons of butter, 2 tablespoon of flour and the liquid from the roaster. Stir over a low heat. Add the reserved ½ cup wine a little at a time and mix well. Pout over the ham in the roasting pan and bake until tender (about 25 minutes to the pound) in a preheated 375° oven. Baste at least every ½ hour with juices from the pan.
NOTES : There are hams and hams. This recipe is intended not for the canned or cellophane-wrapped hams available at your supermarket but for the so-called "country" ham which requires precooking preparation. A gourmet feast will repay you for the loving care these hams call for.