Heat the butter and half the oil in a large pan and gentle fry the onions, garlic and bacon until onions are soft, remove from the pan and put to one side.
Add rest of oil and heat through to brown the venison.
Leave the venison in the pan and stir in the flour, wine and juice and rind of orange.
Return the onions and bacon to pan with the sweet potato and stir well, add sufficient stock to just cover and simmer for approx. 45 min. until meat is tender, stirring occasionally to prevent sticking.
At end of cooking time stir in mushrooms and allow to cool thoroughly, then place in an ovenproof dish approx.10"x8". Place a pie funnel or upturned egg cup in centre to help support pastry.
Assembling the pie
Preheat oven to 220°C/(200°C for fan assisted ovens)/Gas 7
Roll out one pastry block to a rectangle approx.12" x12" and using a sharp knife, cut into strips about 1" wide.
Brush rim of dish with beaten egg, and use strips to form a pastry rim all round. Brush pastry rim and arrange pastry strips on top in a diagonal pattern.
Roll out second block of pastry as above, cut and continue to arrange over filling to give a lattice effect. Brush the first layer with beaten egg so the second layer sticks to it.
Trim off excess pastry, use trimmings to form a top rim, pressing edges of lid firmly all round, brush again with egg and bake for 40-45 min. until pastry is risen and golden.
Delicious served with parsley and garlic flavoured mash and red cabbage.
Janet's Top Tip - The filling is really easy to prepare in advance and store overnight in your fridge or freeze before hand.