a. Ensure your oven is clean and in good working order.

b. Place the oven rack in the center position.

c. Allow the oven to fully preheat before proceeding.

a. In a bowl, combine coarsely ground juniper berries, blueberry jam, fresh thyme leaves, Worcestershire sauce, honey, gin, olive oil, and ground cinnamon.

b. Mix well to create the marinade.

a. Season the 2 kg leg of lamb with 1 tsp salt and 1 tsp freshly ground pepper.

b. Place the seasoned leg of lamb in a roasting pan.

a. Pour the prepared marinade over the leg of lamb, ensuring it's evenly coated.

b. Cover the lamb and let it marinate in the refrigerator for at least 2 hours or overnight.

a. Remove the marinated leg of lamb from the refrigerator and let it come to room temperature.

b. Preheat the oven to 350°F (175°C) if not already done.

c. Place the lamb in the preheated oven and roast for approximately 1 hour and 30 minutes to 2 hours or until the internal temperature reaches your desired level of doneness.

d. Baste the lamb with the marinade juices during roasting.

a. While the lamb is roasting, make the gravy by using the drippings from the cooked leg of lamb.

b. In a saucepan, heat 2 tbsp of flour and cook until it turns golden brown.

c. Gradually whisk in 2 cups of lamb stock and 2 tbsp of red wine.

d. Simmer the gravy, stirring constantly, until it thickens.

e. Season with salt and pepper to taste.

a. Once the lamb is done, remove it from the oven and let it rest for about 15 minutes before carving.

b. Carve the leg of lamb into slices and serve with the prepared gravy.