1. Leave the gammon out of the fridge for 15mins before cooking.
2. Place gammon in a large saucepan and add the onion and 2 litres of cola.
3. Bring to the boil, then reduce to simmer with lid on for 2hrs 30mins.
4. Remove gammon from saucepan and allow to rest for at least 30mins.
5. For the glaze add honey, syrup, brown sugar, wholegrain and English mustard, cloves and cinnamon to a low heat saucepan and gently stir for approx. 5-10mins.
6. Heat the oven to 180°C . Place the gammon onto a roasting tray. Cut off the thick layer of fat (if required) leaving only a thin layer. Score the fat in a diamond pattern and baste with the glaze. Roast for 15mins. Remove from the oven and glaze again. Return to the oven and roast for a further 15mins.
7. Remove and rest gammon for up to 15mins.
8. Serve and enjoy!