Combine the ingredients in a large bowl and beat until thoroughly blended.
Spoon the mixture in to a greased 7 x 11 inch tin and bake at 180ºC (fan 160ºC / Gas mark 4) for 25 minutes or until the cake has risen and the top springs back when lightly pressed.
Sift the icing sugar into a bowl and gradually add the lemon juice until the icing becomes thick and glossy. Spread or drizzle on top of the cooled cake.