Chop the celery and carrots into small pieces. Add the pheasant legs, vegetables and chicken stock to a slow cooker along with some rosemary and thyme. Slow cook the meat for at least 6 hours.
When the pheasant is cooked remove it from the slow cooker. The meat should fall off the bone. Shred it into pieces, making sure to remove any small bones and sinew.
Strain the chicken stock and vegetable mixture through a sieve. Discard the vegetables. Add a pinch of saffron and mix so it dissolves into the stock.
Start the paella. Fry the chorizo, onions and peppers in a little oil for 5-10 minutes. Then add the finely chopped garlic and cook for a further minute.
Now add the rice and mix in. Add the stock a ladle at a time until the rice starts to become soft. Then add the chopped tomatoes, followed by the peas a few minutes later.
Mix in the pheasant meat, season the paella to your liking and serve.