Preheat the oven to 180ºC/350ºF/gas 4. Line 2 large baking trays with greaseproof paper.
Melt the butter in a small pan over a low heat, then stir in the golden syrup. In a small bowl, combine the bicarbonate of soda with 3 tablespoons of boiling water, then stir it into the butter mixture.
Combine the flour, oats, sugar and coconut in a medium bowl. Make a well in the middle, then add the butter mixture, vanilla extract and orange zest. Give the wet ingredients a good mix, then gradually stir in the dry ingredients to combine.
Place heaped tablespoons of the mixture onto the prepared baking trays, leaving a rough 3cm gap between each one. Place in the hot oven for around 10 minutes, or until golden, then transfer to a wire cooling rack to cool completely.