Preheat oven to 180 degrees C. Grease and flour a 20x30cm pan. Mix together the topping ingredients - brown sugar, chopped nuts and 1 cup coconut. Set aside.
In a large bowl, mix together the flour, sugar, bicarb soda and salt. Make a well in the centre and pour in the eggs and fruit cocktail with juice. Mix well and pour into prepared pan. Sprinkle with topping mixture.
Bake in the preheated oven for 30 to 35 minutes, or until a toothpick inserted into the centre of the cake comes out clean.
In a saucepan, combine margarine, golden syrup, evaporated milk and flaked coconut. Cook, stirring constantly, until mixture boils and thickens. Pour over cake and place back in oven for few minutes until it bubbles.