To make the glaze, put the Guinness, honey and sugar into a saucepan.
Reduce by almost half to form a sweet syrupy glaze, and then leave aside to cool.
Preheat oven to 180°C/350°F/gas 6. Season the pork with pepper and salt and place on a baking tray, roast for 20 minutes.
Reduce the heat down to 140°C/280°F/ gas3.
Remove the pork from the oven and brush generously with the glaze, (reserving a few tbsp) cook for a further 40-50 mins, occasionally basting with the glaze.
Remove the pork from the roasting tray and leave to rest. Pour the remaining glaze into the tray and add the wine or water.
Place the pan on the heat and bring everything to the boil, simmer for a few mins until you reach a thick gravy. Carve the pork into thin slices and serve with colcannon or mashed potatoes. Drizzle a little syrup on each plate.