Place the ham slices in a shallow baking dish. Pour over port. Marinate overnight in the refrigerator.
Preheat the oven to 220 C / Gas 7.
Pour off the port from the ham into a medium bowl. Roll up each slice of ham lengthways and place side by side in the baking dish. Mix the cream, curry powder and tomato puree into the port. Pour over the ham, making sure to get all of the slices covered. Dot the top with small pieces of butter.
Bake uncovered for 45 minutes in the preheated oven or until the ham begins to brown on top.