Position an oven rack in the middle of the oven and preheat to 425 degrees F.
To prepare the chicken, lift the skin gently with a knife and insert some small pieces of butter and slices of lemon under the breast.
Make a ball of the stuffing and place in the cavity. Tie the chicken together with a string. Lay 6 pieces of streaky smoked bacon over the chicken. Season with salt and freshly ground pepper. Rub salt and butter into the skin. Heat oil in roasting pan and put the chicken and the onion into it. Cook for 1 hour and 30 minutes. Baste the chicken thoroughly every 20 minutes. After 1 hour and 10 minutes remove the crispy bacon slices and place them on a dish for serving. Return the chicken to the oven for another 20 minutes.
While the Chicken is cooking, start the gravy:
To make stock, combine the giblets with a bay leaf and an onion in a saucepan. Cover with water and bring to a boil. Add carrot and peppercorns. When the chicken is cooked, transfer it to a plate and keep warm. Put the roasting tin on heat and drain off fat with a spoon. Add 2 tablespoons of flour to the juice. Keep stirring. When the juice is brown add the stock. Sieve the gravy to remove any lumps. Add a splash of white wine if desired.
In a medium saucepan melt the butter and sweat the onions until translucent. Combine the chopped herbs, breadcrumbs, beaten egg, lemon juice and zest in a medium-mixing bowl. Add onions and mix thoroughly.
Preheat oven to 425 degrees F.
Parboil the potatoes. Coat them in flour. Put in a roasting tin with very hot sunflower oil. Roast for 30 minutes.