Pre-heat your oven to 170°c (150°c for fan assisted oven or Gas Mark 4) and line a 2lb loaf tin with greaseproof paper. Set aside.
In a large bowl, cream together the margarine and sugar until light and fluffy.
Add the eggs one at time, ensuring they are mixed through before adding the next. Add the lemon extract.
Sift in the flour and gently fold to create a batter. Add the sultanas and mix to ensure they are evenly distributed.
Transfer the batter to your pre-lined tin and bake in your pre-heated oven for about one hour until risen, golden and a skewer inserted comes out clean.
Leave to cool in the tin for a few minutes before transferring to a wire rack to cool completely.