Soak your sultanas in your tablespoon of rum for 30 minutes to an hour before you begin baking.
Set your over to 140°C Fan/160°C/320°F/Gas mark 3.
Grease your loaf tin and then line it with a piece of your greaseproof (parchment) paper but cutting one piece that will sit across the long sides and base. The shorter ends of the tin will be not covered, but as the tin is greased they will be fine as long as your tin is ok.
Add your butter, sugar, golden syrup, stem ginger syrup and treacle to your small saucepan and melt slowly on a low heat. Leave to cool for a few minutes and then add to your mixer bowl.
Mix your bicarbonate of soda (baking soda), milk, and sour cream together and set aside for a few minutes so that it curdles a little.
Sift your flour, ginger, cinnamon, cloves and salt and set aside.
Add your egg to the cooled mixture in your mixer bowl along with a heaped desert spoonful of flour mixture.
Beat on a low setting until just combined.
Add the rest of your flour and beat on a medium setting for about 10 seconds until combined.
Add your milk mixture and beat on a low setting until combined, stop and scrape the sides and base of your bowl down with your spatula to ensure all of your mixture is incorporated
Beat on medium-high for 10-15 seconds, the cake batter will be quite runny.
Fold in your soaked sultanas and chopped stem ginger.
Pour your batter into your prepared tin and bake in the centre of your oven for 1 hour and 10-15 minutes, or until a skewer inserted into the centre of the cake comes out clean.
10 minutes before your cake is due to come out of your oven make your dark rum syrup.