Preheat the oven to 200C/180C fan or GM6. Grease and line a 20cm square tin.
Begin by mixing the ground flax seed with the water and bicarbonate of soda, and leave to thicken.
Blend together the bananas, oil, sugar and orange juice. Add the ground flax seed/water mixture.
In a large bowl, mix together the flour, desiccated coconut and grated carrot.
Mix the wet ingredients with the dry, and stir to blend. Pour the mixture into the tin and place in the oven. Set the timer for 30 minutes.
After 30 minutes, turn the oven temperature down to 180C/160c fan or GM5. Cook for a further 30 minutes, or until a skewer comes out clean and the cake is springy to touch.
Cool in the tin for 10 minutes, then cool on a wire rack until cold. To make the drizzle icing, mix the icing sugar and orange juice together and drizzle over the cake. Divide in 16 pieces.
Keeps for 2-3 days in an airtight tin, and freezes well.