Preheat the oven to 180 degrees C. Grease a 29cm x 19cm slice tin and line base and two long sides with baking paper, extending paper 5cm over sides.
Using electric beaters, beat the butter, lemon rind and 2/3 cup of the sugar in a small bowl until light and fluffy. Add the eggs, one at a time, beating well after each addition. Fold in the flour, desiccated coconut and yoghurt until combined.
Spread the mixture into the prepared tin and smooth the surface. Bake for 25-30 minutes or until a skewer inserted in the centre comes out clean.
Meanwhile, combine the juice, remaining sugar and 2 tablespoons water in a small saucepan with over medium heat. Stir until sugar dissolves. Bring to the boil. Boil for 3-4 minutes or until syrup thickens slightly. Pierce cake all over with a skewer. Pour over half the hot syrup. Set cake aside in tin for 5 minutes before turning out onto a wire rack. Serve cake warm drizzled with the remaining syrup and sprinkled with the flaked coconut.