Preheat oven to 160 C / Gas 3. Grease a 2lb loaf tin or line with a loaf tin liner.
Mix flour, baking powder, bicarbonate of soda and salt in a bowl. Stir bananas, milk and cinnamon in another bowl. Beat butter and sugar in a third bowl until light and fluffy. Add eggs to butter mixture, one at a time, beating well after each addition. Stir banana mixture into butter mixture. Stir in dry mixture until blended. Fold in chocolate chips until just combined. Pour batter into prepared loaf tin.
Bake in the preheated oven until a skewer inserted into the centre of the loaf comes out clean, about 70 minutes. Cool in the tin for 10 minutes before removing to cool completely on a wire rack before slicing.