Preheat oven to 350°F / 180°C / Gas mark 4.
Butter and flour an 8x5 loaf pan
Sift flour, baking powder and salt together, set aside.
Using an electric mixer, beat butter and cream cheese together until light and fluffy, about 4 minutes.
Add sugar and beat to combine. Scrape down bowl and add eggs, one a time, mixing thoroughly before adding in second egg.
Add vanilla and milk, beat on low just to incorporate.
Add flour mixture on low, beating just until mixture is almost incorporated, but not fully.
Scrape down bowl, making sure to scrape the bottom of the bowl; beat on low for 30 seconds to mix well.
Add 1/3 of the batter to the loaf pan. Smooth to make an even layer in the bottom of the pan.
Then add blueberries to the remainder of the batter and gently fold berries into the mixture, using a rubber spatula.
Add remaining batter to loaf pan and smooth the top.
Bake for 60 - 70 minutes, or until a knife inserted comes out clean.
Cool cake in pan for 10 minutes, then invert cake to release.
Cool pound cake completely on wire rack. Glaze, if desired, once cooled.