Preheat oven to 180oC. Grease and line a 19cmx29cm slice pan (at least 3cm deep) with baking paper.
Combine flour, oats, brown sugar, desiccated and moist coconut in a large bowl.
Heat butter and golden syrup in a saucepan over low heat. Cook, stirring occasionally for 8 minutes or until butter has melted. Remove from heat. Add bi-carb and boiling water.
Pour into dry ingredients and stir to combine.
Press evenly into prepared pan. Bake for 25 to 30 minutes or until golden. Cool in pan and cut into squares.