To Cook: Place the joint in a large saucepan. Add chopped vegetables and peppercorns. Cover with cold water. Bring to the boil, then simmer gently for approximately 20 minutes per ½ kg. Set oven to Gas Mark 6, 200ºC (400ºF). Remove the joint from the saucepan. Reserve liquid. Remove the rind and score the fat. Place the joint on a roasting dish. Spread with mustard and breadcrumbs, sugar and a knob of butter. Place in the oven for 15-20 minutes. To Make the Sauce: Melt the butter, add the flour and mustard. Cook for a minute or two. Whisk in the cooking liquid and cream. Bring to the boil. Reduce the heat and simmer for 3-4 minutes. Taste for seasoning. The sauce should have the consistency of thin cream. Keep warm. To Cook the Cabbage: Place the cabbage in a saucepan and barely cover with some of the reserved cooking liquid. Bring to the boil. Reduce to a simmer and cook for 2-3 minutes. Drain well and toss in butter. Season to taste. Slice the bacon and serve on the bed of cabbage, a little of the mustard sauce and of course floury potatoes.