Line the tin with a double layer of greaseproof paper. Place all the fruit in a bowl and mix well. Beat together the butter and sugar until light and fluffy. Beat the eggs and golden syrup, then add to creamed butter and sugar. Fold in the sieved flour and gently mix in the prepared fruit and half of the whiskey. Turn into the prepared tin, spread with a knife, leaving a slight hollow in the centre. Bake at 150 degrees for 3 1/2 hours. Check regularly! Leave cake in the tin until cold and remove paper. Spoon over the remaining whiskey. Wrap the cake in greaseproof paper and store in an airtight container. Decorate the cake first with a layer of jam and then apply the marzipan. The cake is now ready for icing (last step optional).