Preheat oven to 350 degrees F. Lightly grease a loaf pan. In a bowl, cream together butter and sugar until light. Beat in eggs, vanilla and zest. Sift together dry ingredients then mix into egg mixture alternately with milk until just combined. Gently fold in blueberries. Spoon the batter into pan. Bake for 40-45 minutes, or until a toothpick inserted into the centre of loaf pulls out clean. Combine glaze ingredients. When loaf is baked and still hot in the pan, brush with glaze. For the presentation shown in the photograph, when cool unmould loaf and slice into 12 slices. Set two slices on each of six plates. Serve with a scoop of vanilla ice cream and garnish with fresh blueberries and mint.