Heat oven to 160/140C fan/gas 3. Grease and line a 2lb tin with baking parchment. Mix the flour, bicarb, baking powder and pinch of salt in a large bowl.
Mix the bananas, syrup, eggs and yogurt. Quickly stir into dry ingredients, then gently scrape into the tin. Bake for 1 hour 10 min approx or until a skewer comes out clean.
Cool in tin on a wire rack. Eat warm or at room temperature.