Roast turkey and stuffing

Name: Roast turkey and stuffing
Ingredients: 4.5-5.5kg/10-12lb whole turkey, with giblets; 1 onion, halved; 1 carrot; 2 celery sticks; 2 sprigs of fresh parsley; 2 sprigs of fresh thyme; 175g/6oz butter; flaked sea salt and freshly ground black pepper; 85g/3oz butter; 175g/6oz onions, finely chopped; 225g/8oz fresh white breadcrumbs; 2½ tbsp chopped mixed fresh herbs (parsley, chives, thyme or sage); 1.2 litres/2 pints stock (see above, or chicken stock); 1 tbsp softened butter; 1-2 tbsp plain flour