Preheat the oven to 180oC /
Gas 4. Then line a 23 x 13 cm loaf tin with greaseproof paper and grease
Cream the butter or margarine with the
sugar until light and fluffy. Beat in the egg yolks. Add the lemon rind
and juice and stir until blended. Set aside.
In another bowl, sift together the flour
and baking powder three times. Fold into the butter mixture in three
batches, alternating with the milk. Fold in the walnuts. Set aside.
Beat the egg whites and salt until
stiff peaks form. Fold a large spoonful of the egg whites into the
walnut mixture to lighten it. Fold in the remaining egg whites carefully
until the mixture is just blended.
Pour the batter into the prepared tin
and bake until a skewer inserted in the
centre comes out clean, about 45 - 50 minutes.
Cold in the tin for 5 minutes before
turning out on to a wire rack to cool completely.