Cream butter; gradually add 1 cup sugar, beating at medium speed until well blended. Add eggs, one at a time, beating well after each addition. Combine flour, baking powder, and salt; add to creamed mixture alternately with milk, beginning and ending with flour mixture. Stir in grated lemon rind; then fold in blueberries. Pour batter into a greased 8 x4 x 3 inch pan. Bake at 350 degrees for 55 minutes or until a toothpick inserted in the center comes out clean.
Combine 1/3 cup sugar and lemon juice in a small sauce pan; heat until sugar dissolves. Puncture top of bread in several places with a wooden pick; pour lemon juice mixture to soak into bread. Cool bread in pan for 30 minutes.