Melt half of the goose fat in a large pan. Add the onions, ginger, bay leaves and nutmeg, and gently fry until golden-brown – about 20 minutes.
In a separate pan make a stock, fry the goose neck, gizzards and heart in a tablespoon of goose fat until browned. Add two litres of water and leave to simmer. When you are ready to use the stock, it will need to be strained.
Tip the cooked onion mixture into the cooked pearl barley. Add the lemon zest, grated eggs, chopped prunes, parsley, grated apple, 300g/10½oz chicken livers any other liver (chopped) from the goose giblets. Add lots of black pepper plus two teaspoons salt. Mix everything together using your hands.
Mix the chopped sage and rosemary leaves with a few heaped teaspoons of salt.
Preheat the oven to 200C/400F/Gas 6.
Stuff the goose with the pearl barley mixture, rub the skin with a little oil and sprinkle over the rosemary and sage salt. Transfer to the oven and roast for about 15 minutes per 450g/16oz plus an extra 20 minutes (2-3 hours depending on the size of your goose), or until the juices run clear and the skin is crisp.
Remove the cooked goose from the roasting tray, cover and set aside to rest while you make the gravy.
For the gravy, remove most of the fat from the roasting tray, leaving approximately two tablespoons remaining in the tray. Place the tray over a low heat, add the flour and mix to form a loose paste. Cook for 2-3 minutes, then add the Madeira and port. Bring to the boil while stirring constantly and simmer for two minutes before pouring in 1.5 litres/2½ pint stock (made earlier from the goose neck and gizzards). Bring to the boil before straining and serving in a jug.