In a large oven-proof casserole, sauté the bacon until crisp.
Remove the bacon and pour off the fat.
Place the garlic and rosemary inside the cavity of the chicken and place the chicken in the pot.
Surround the chicken with potatoes, turnips, carrots and bacon and pour over the sherry or verjuice.
Drizzle some olive oil over the chicken,sprinkle with sea salt flakes and freshly ground black pepper and replace the lid on the casserole.
Bake at 150 C for 2 hours, removing the lid 30 minutes before the end of cooking time if you'd like to brown the chicken.