1) In a large bowl, using a mixer, combine the butter and sugar until creamy. Add the eggs, 1 at a time, beating well after each addition.
2) Add the flour and milk alternately, beginning and ending with the flour. Stir in the lemon extract. Spoon the batter into the prepared pan.
3) Place pan in a cold oven and heat oven to 160 degrees C/Gas 3. Bake cake for 1 hour. Increase the temperature to 180 degrees C/Gas 4 bake for 30 minutes more.
*Cook's Note: Do not open the oven door while baking.
Cool the cake in the pan for 10 minutes, and then turn out onto a wire rack to cool.
Note: In the US cake flour is a special blend of flour which produces a lighter cake. To substitute, sift together 350 g of plain flour with 70 g of cornflour.