Combine the caster sugar and 185g of the butter untill light and fluffy. Mix in the eggs. Fold in the flour gradually, alternate with the poppy seed and milk mix. Finally stir in lemon rind. Alternatively add the ingredients to an electric mixer. Beat on high for 5 minutes until the mixture is pale and thick. Pour into the pan and bake in the oven for 40 minutes or until a skewer inserted into the centre comes out clean. Turn onto a wire rack to cool.