In a bowl combine the peaches, blueberries, brown sugar, cinnamon, nutmeg, and cornstarch. Set aside.
Roll out the short crust pastry and place on a sheet pan or round baking sheet. Arrange the peaches on the pastry. If using a rectangle/square arrange in rows, or if making a circle arrange in a circle. Top with the blueberries and then fold the remaining crust over the ends of the fruit.
Combine the cream and egg and stir until mixed. Using a pastry brush, brush the mixture over the crust and then dust with the turbinado sugar.
Bake for 50 minutes or until the crust is a golden brown and the filling is bubbling.