In a large bowl, combine ground ham, ground beef, breadcrumbs, onion, salt, pepper, curry powder, sage, and allspice. Mix to combine. Add milk and eggs and mix to combine.
Pack mixture into a 5x9x3-inch loaf pan.
In a medium bowl, stir together brown sugar, vinegar, and mustard and mix until thoroughly combined. Pour half of the sauce over the loaf.
Bake for 90 minutes. Remove from the oven and serve with remaining sauce on the side.