Cream butter with sugar. Beat in eggs one at a time, stir in lemon rind. Fold in sifted flour and milk. Turn into a greased pudding basin, cover with 2 thicknesses of greased greaseproof paper, tie with string and steam 11/2 hours. Alternatively, spoon mixture into 6 individuals greased 1-cup-size moulds, cover and steam 25 minutes. Serve with jam, golden syrup or sweet sauce. Serves 6.