Take pheasant and put half of the thyme and bay leaves into cavity then rub in 2/3 salt and pepper over the bird and smear over the butter. Place bacon over the pheasant and place into a casserole dish with a lid and put in oven for 40-50 minutes until juices run clear.
Once the pheasant is done and cool enough to handle strip the meat from the bird only discarding bones and skin. Shred the meat with your hands, then dice bacon and put to one side.
Saute the leeks, onions and celery in a frypan with a little olive oil. Add the stock and cook until reduced slightly then add the meat from the bird including bacon and if it is still slightly watery add 2 tablespoons of cornflour to thicken.
Line a loaf tin with the pastry and spoon in the mixture.
Trim the excess pastry from the tin and roll to make a lid. Place lid over the tin and crimp edges then poke 2 small holes in top of pie to let steam escape. Use any leftover pastry to make a decoration for the top of the pie. Brush the top of pie with olive oil or a glaze of choice.
Preheat oven to 200 degrees C and place the pie in oven for 30-40 minutes or until golden brown.