Preheat oven to moderate, 180C. Lightly oil and line a 10 x 20cm loaf pan. Sift flour and cinnamon together into a large mixing bowl. Stir in sugar.
In a large jug, combine banana, butter, eggs, milk and vanilla. Using a wooden spoon, lightly mix banana mixture into flour mixture until just combined.
Pour into pan, smoothing the top. Bake for 40-45 minutes, until cooked when tested with a skewer. Cool in pan for 5 minutes before turning onto a wire rack to cool completely.
