Grease and line 20cm deep cake tin. Preheat oven to 160 degrees C.
Beat together the butter, caster sugar, eggs, self-raising flour, baking powder, the lemon rind and enough milk to make a fairly soft consistency.
Put into tin and bake for about an hour until well risen and springy to touch.
Mix together icing sugar and 3 tablespoons lemon juice in a pan over very low heat.
As soon as cake comes out of oven prick top of cake with fine skewer and pour the icing/syrup over it. Leave to cool in tin for 10 minutes then transfer to rack to finish cooling.
Lemon rind tip
I take the rind off the lemon with a potato peeler - it's much easier than grating. Then, using a food processor or blender, blend the rind with the sugar. The lemon oil goes into the sugar and makes the finished cake yellow and taste much more lemony.