Grease a 9-1/4x5-1/4-inch (23x13-cm) loaf pan and sprinkle with fine breadcrumbs.
Preheat oven to 350°F (175°C).
Toss raisins in a little flour.
Sift remaining flour, cornstarch and baking powder together.
In a large bowl, cream butter or margarine and sugar until pale and fluffy.
Beat in 1 egg.
Gradually beat remaining eggs into creamed mixture, stirring in a little flour mixture between each addition.
Fold in remaining flour mixture.
Stir lemon peel, almonds, raisins and rum into mixture.
Turn batter into prepared pan; smooth the surface.
Bake 1 hour 5 minutes or until a skewer inserted in center comes out clean.
Remove cake from pan; cool on a rack.