The day after you marinate the pheasant pieces, you can get on with the cooking.
What you do is wipe the marinade off the pheasant, and brown them in a pan with butter. Then you set them aside and cook mushrooms in the buttery-pheasanty oil before again removing these to a plate. Next you brown some baby onions and remove them to yet another plate. (The "baby" onions I got at Coles were suspiciously large, so I used half the number of onions the recipe says to, and cut them into quarters).
Ready to be cooked
At this stage, you chuck some cubed pancetta into the pan, and let it cook until crisp, at which point you add flour, stirring until incorporated into the liquid in the pan. Then you slowly add Martini Rosso (AKA red vermouth), game stock (I used chicken, but don't tell anyone), and the strained marinade liquid, stirring well to make sure it's all incorporated.
Then you return the pheasant, mushrooms and onions to the pan, and cook in the oven slowly for 2 hours. I found, that with my very reduced quantities, the pan was so large that the pheasant pieces were not submerged in the liquid. So, I carefully transferred everything to a smaller ceramic dish, and covered it with foil to cook.
Out of the oven, it looked like this...
Here, you strain the liquid off, and reduce it in a pan until slightly thickened and no longer watery. Then you put the liquid back in the dish, and you can leave it in the fridge for a couple of days until ready to eat.