Place the chicken drumsticks into a bowl and season with sea salt and freshly ground black pepper. Add the bay leaves, rosemary sprigs and garlic, then cover with the wine. Leave to marinate for a minimum of 1 hour (ideally overnight) in the fridge.
Heat half of the olive oil in a large heavy-based stockpot over medium heat. Add the onion, celery, carrot and pancetta. Cook, stirring occasionally for 5 minutes, or until the onion is soft and golden. Add the mushrooms and cook for a further 4 minutes, stirring occasionally. Transfer the onion, pancetta and vegetable mixture onto a plate and set aside.
Remove the chicken from the fridge. Drain the chicken, reserving the marinade, and pat dry with paper towel. Toss the drumsticks in flour, shaking off any excess. Heat the remaining olive oil in the stockpot over medium heat. Lightly brown the chicken drumsticks, in batches. Return all chicken drumsticks to the stockpot, then pour over the wine and herbs the chicken was marinading in. Cook until the liquid has almost evaporated.
Stir in the tomatoes, sugar and chicken stock. Bring to the boil, then add the onion, pancetta and vegetable mixture. Cover and leave to simmer for 30 minutes, or until the chicken is tender.
Remove from the heat and stir through parsley. Serve immediately – buon appetito.