Place the ham in a large heavy based saucepan, add the studded onion, carrots, bay leaf. Add enough water to cover the ham completely. Bring to the boil then reduce the heat and allow to simmer for about one hour, approximately 20-25 minutes / 500 g or pound. Remove from the heat and allow the ham to cool in the cooking liquor.
In a bowl, combine the marmalade, brown sugar with honey.
Preheat the oven to 160˚C/ 325˚C.
Place the boiled ham on a roasting tray. Using a sharp knife carefully remove the skin from the ham, then gently score the fat.
Spread the glaze over the ham with a spoon.
Place into the oven for 10 - 15 minutes until golden brown then remove from the oven. Using a pastry brush, brush any missing spot of the ham and let it rest for 20 minutes.
Next, prepare the gremolata. in a bowl, combine the parsley, garlic, lemon zest and juice with the olive oil, salt and pepper.
Carve the ham and sprinkle the gremolata over. Serve immediately with vegetable and a side of colcannon mash.