Pre-heat oven to 160ºC (325ºF). Grease and flour and line a loaf tin set aside.
In a large bowl, whisk together flour, baking powder, sugars, and salt. In another bowl, whisk together eggs, oil, buttermilk and vanilla. Add the wet ingredients to the dry ingredients and fold in gently until just combined. Then add in the mashed banana.
In a separate bowl toss blueberries in 2 tbsp flour until coated. Add to batter and fold gently.
Pour into the loaf tin and spread evenly. Sprinkle with a few blueberries on top.
Bake for 45-60 minutes until a toothpick comes out clean.