Preheat the oven to 170°C/325°F/ Gas Mark 3. To make the pie filling sauté the bacon pieces and shallots gently in the oil for 6-8 minutes. Remove from the pot with a slotted spoon, leaving the oil inside, and set to one side.
Add the diced venison a little at a time to the flavoured oil in the pot and seal. Stir in the garlic, tomato purée and black pepper, sprinkle over the flour and stir. Return the cooked bacon and shallots along with the mushrooms to the pot.
Stir in the red wine, hot stock, juniper berries, bay leaves and thyme. Bring to a simmer on the hob, place on the lid and transfer to the oven to cook 1 hour. Once the filling is cooked remove the bay leaves, any herb twigs and season to taste.
Increase the oven temperature to 200°F/400°F/Gas Mark 6. To make the pie dust a work surface and a rolling pin with a little flour and roll out the pastry to approximately 5-7mm thick. Turn the pie dish upside down and use as a guide to cut a circle about 1cm larger than the top. Cut some thin strips from the remaining pastry to use around the rim of the dish.
Place the cooked filling into the pie dish. Brush some of the beaten egg mix around the edges of the dish and stick on the pastry strips, joining up where necessary.
Brush the pastry strips with some more of the beaten egg mixture and place on the pastry top.
Press the pastry down gently around the edges to seal. Brush the top with the remaining beaten egg. Cook for 20- 25 minutes until puffed up and deep golden brown. Serve with creamy neeps and tatties on the side.