1) Using 2 pastry blenders, blend the butter, shortening, flours, salt and icing sugar. Whisk the liquids in a separate bowl and pour over dry ingredients. Incorporate all the ingredients without overworking the dough. Toss the additional flour on top and scrape sides of bowl. Chill if time permits. Divide dough into 2 pieces. Roll out dough for the bottom crust. Place in a pie dish and refrigerate while working on filling.
For the filling:
2) Mix all ingredients except butter and pour into chilled pie crust. Dot with butter. Brush edges of crust with egg wash.
3) Preheat oven to 210C/Gas 7.
4) Roll out top crust and press in decorative vents and slits before covering pie or make a lattice crust. Crimp edges and place a pie bird in the centre. Brush with egg wash and garnish with raw sugar. Bake for 15 mins. Decrease temperature to 190C/Gas 5 and bake for an additional 45 to 50 mins.