Preheat oven to 180°C. Lightly grease baking trays with butter. Put flour and sugar into a mixing bowl. Add in oats and desiccated coconut. Stir the mixture so that it's well mixed.
Combine butter and golden syrup in a saucepan and stir over gentle heat until butter has melted and the mixture turns smooth. Remove from heat. Dissolve bicarbonate of soda into water, then add to the butter mixture which should foam up immediately.
Add this mixture to the flour mixture and stir well to combine all the ingredients. Take out about a tablespoon of the resulting mixture. Roll lightly into balls and place on the prepared trays.
Flatten each ball with a fork to create a pattern. Bake in preheated oven for 18-20 minutes or until golden brown.
Leave cookies in the tray for two to three minutes before transferring them to a wire rack to cool.