Preheat the oven to 175°C. Lightly spray a 9-by-5-by-3-inch metal loaf pan with non-stick cooking spray and set aside.
In a medium bowl, whisk the flour, baking powder, bicarbonate of soda, 3/4 teaspoon dry mustard, salt and cayenne until combined. In a large bowl, whisk together 180ml milk, the oil, 1 tablespoon honey and the eggs until smooth. Stir in the dry ingredients until just combined. Then fold in the ham, grated cheese (reserving some for sprinkling on top), the diced cheese and spring onions.
Pour the batter into the prepared loaf tin and sprinkle the top with the remaining cheese. Bake until well risen, golden brown and a skewer or cake tester inserted in the center comes out clean, 40 to 45 minutes.
Cool in the pan for 10 minutes. Meanwhile, in a small microwave-safe bowl, stir together the remaining 1 tablespoon each honey and milk and the remaining 1 1/2 teaspoons dry mustard until smooth. Heat in the microwave until hot and bubbling, 20 to 30 seconds. Turn the loaf onto a wire rack and generously brush with the warm glaze. Cool completely.