Weigh the meat to calculate cooking times working on 20 mins per 450g, plus 20 mins.
Put the meat in a large pan, cover with cold water and bring to the boil, adding any flavourings you may wish (cinnamon, bay, peppercorns, coriander seeds and onion work well).
Boil for half the calculated cooking time, periodically skimming and discarding any white froth that rises to the surface. Drain, and leave to cool a little. Remove the top layer of skin, leaving a thin layer of fat around the meat.
Place in a foil-lined roasting tin, cover with more foil and bake for the remaining cooking time at 180C/160C fan/gas 4. Twenty to thirty minutes before the end of cooking time, brush with a glaze such as a mixture of maple syrup and coarse-grain mustard.