Preheat oven to 150 degrees C. Lightly grease and flour one 25cm ring cake tin.
Combine margarine, white sugar, eggs, buttermilk, sifted flour, bicarb soda, baking powder and lemon essence and beat with an electric mixer for 3 minutes at medium speed. Pour batter into prepared pan.
Bake at 150 degrees C for one hour. Remove cake from pan after it has cooled.