1. Put flour, baking powder, sugar and zest into a bowl and mix well before adding the oil, juice and the water.
2. Mix thoroughly to make sure all is combined well.
3. Pour into a lined cake tin and bake for 30 minutes until fully cooked at around 200 Celcius.
4. When cool its definitely worth making a glaze for the top, this is done by sieving the icing sugar and stirring in lemon juice until the consistency is wet enough to pour over the cake.