Preheat the oven to 180°c and line a loaf pan with baking paper.
Using the stand mixer fitted with the paddle attachment, cream the butter and sugar on medium speed until pale and fluffy. Then continue on medium speed add one egg at a time, beating well after each addition.
Add bananas to mixture and beat again on medium speed until well combined. Stir in the flour and bicarbonate of soda followed by the mixed frozen berries.
Pour the mixture into the prepared loaf pan and bake for 65-75 minutes until a skewer inserted into the bread comes out clean and the bread has risen well. Turn onto a wire rack to cool then slice to serve.