Bake at 350 degrees F (175 degrees C). Grease and flour one 8x10 inch cake pan.

In a bowl, cream the butter or margarine with the granulated sugar. Beat in the eggs, then the lemon rind and milk.

In another bowl, stir together the whole wheat flour, all purpose flour, baking powder, and salt. Beat into the creamed mixture. Spread half the batter evenly into the prepared pan. Arrange the peach slices on top and sprinkle with the brown sugar combined with the ground cinnamon. Spread the remaining batter on top.

Bake at 350 degrees F (175 degrees C) for 50 minutes. Let cake cool on a rack. Because this cake is so moist, it is easiest to serve it directly from the baking pan. It should be stored in the refrigerator. Makes 16 servings.