Heat the oil in a large, heavy-based saucepan over low-medium heat. Add the onion, pancetta and garlic and saute until golden. Add celery, carrot and potato and cook for 5 minutes, until they begin to colour. Add the bay leaf, passata, tomato paste and stock and bring to the boil. Add the beans, pasta, zucchini and basil leaves, decrease the heat to low and gently simmer for 30-35 minutes, until the pasta and vegetables are cooked. Stir in the parsley and season with salt and pepper.