Melt the butter in a large saucepan, sprinkle in the flour and cook for 1 minute. Add the milk, a little at a time, stirring after each addition, then add the stock cubes and Worcestershire sauce and season with salt. Bring to the boil, stirring with a wooden spoon until the mixture thickens. Stir in the sherry and Tabasco sauce. Add the turkey, mushrooms, carrots and onions and heat through gently but thoroughly. Stir through the chopped parsley, then turn the mixture into a 1.8 litre (3 pint) pie dish.
Roll out the pastry on a lightly floured surface and cover the dish, fluting the pastry edges. Make a small hole in the centre to let the steam escape. Decorate with the trimmings. Bake in a preheated oven, 200°C (400°F), Gas Mark 6, for about 20 minutes until the pastry is beginning to brown.
Brush the pie top with beaten egg, then return to the oven for a further 10 minutes until the pastry is puffed up and brown.