Heat the oven to 220C/425F/Gas 7.

Melt the margarine in a large frying-pan, add the onion and fry for 5 minutes until soft and lightly coloured. Add the apple and curry powder and cook gently for another 5 minutes. Sprinkle in the flour and stir until blended. Gradually stir in the stock and simmer, stirring, until thick and smooth.

Stir in the chicken pieces and mushrooms and season with salt and pepper to taste. Cook for a further 5 minutes, then stir in the chopped tomatoes. Pour the mixture into an 850 ml/lV2 pint pie dish.

Roll out the pastry on a floured surface to a shape slightly larger than the top of the pie dish. Cut off a strip of pastry all around edge.

Brush the rim of the dish with water and press the strip of pastry on the rim. Brush the strip with a little more water, then place the large piece of pastry on top. Press to seal, then knock up and flute.

Make decorations with the pastry trimmings, brush the undersides with water and arrange on top of the pie. Brush the pastry all over with the beaten egg and make a small hole in the centre of the pie. Bake in the oven for 30 minutes until golden. Serve at once.