Rub 2 tablespoons of butter around a casserole and dust with 1 tablespoon granulated sugar. Preheat oven to 325 degrees F. Butter the bread with the remaining 6 tablespoons of butter. Scald milk in a pan, add the vanilla pod and the lemon zest. Stir in 1/4 cup granulated sugar. Increase the heat and dissolve the sugar and then remove from the heat. Arrange some of the cut bread overlapping on the base of the casserole. Sprinkle with some of the raisins and candied peel. Place another layer of bread on top - alternating the brown and white slices. Cover with the remaining bread. Sprinkle the remainder of raisins on top and grate the nutmeg over them. Break the eggs into a bowl and whisk. Slowly stirring into the scalded milk (having removed the lemon zest and vanilla pod). Pour this mixture over the bread. Dust with 1 tablespoon sugar and sprinkle with the dry sherry. Allow to stand 1 hour. Before placing it in the oven, pour the 1/2 cup of whipping cream over the pudding. Cook in the preheated 325 degree oven on the middle shelf for 55 minutes.