Place the loin of bacon in a saucepan and cover with cold water. Bring to the boil, then reduce the heat and simmer gently for 20 minutes per 450g.
Transfer the bacon to a roasting tin. Remove all but a thin layer of fat then score the remaining fat in a diamond pattern. Mix together the sugar, mustard and cloves in a small bowl and then spread it over the scored fat in an even layer. Preheat the oven to 180°C/350°F/gas mark 4 and roast the bacon for 20 minutes until the top is nicely glazed. Leave to rest in a warm place for 10 minutes.
As soon as you have popped the bacon into the oven, steam the potatoes for 15-20 minutes until cooked. Cook the frozen peas in a separate small pan for 3-4 minutes.
Drain the peas well and then return to the pan. Season and then add the butter and milk. Blitz with a hand blender until you have a smooth purée. Mash the potatoes until very smooth, then fold in the pea puree until well combined. Season to taste.
Carve the loin of bacon into slices and arrange on warmed plates with the pea and potato mash. Serve with a dish of buttered baby leeks.