Preheat oven to 350°F (175°C). Grease a loaf pan.
In a bowl, cream butter and sugar until light and fluffy.
Beat in eggs, one at a time. Add vanilla extract and lemon zest.
Mix in milk.
In another bowl, combine flour, baking powder, and salt.
Gradually add dry ingredients to wet ingredients, mixing until just combined.
Toss blueberries with 1 tablespoon flour and fold into batter.
Pour batter into prepared loaf pan.
Bake for 60 minutes or until a toothpick inserted into the center comes out clean.
Let cool in pan for 10 minutes, then transfer to a wire rack to cool completely.