Preheat the oven to 180 C / Gas 4. Grease and flour a 20x10cm loaf tin.
Put the dates in a bowl and add just enough boiling water to cover them, add bicarbonate of soda and leave to soak for 10 minutes.
While soaking combine the flour and spices in a bowl. Set aside.
In a saucepan melt the butter, sugar, golden syrup and vanilla. Once melted, slowly add the date mixture, milk and banana. Stir in the boiled mixture until just blended. Pour the into the prepared tin.
Place in the preheated oven and immediately reduce heat to 160 C / Gas 2 1/2 and bake for 50 minutes, or until the top of the loaf springs back when lightly touched. Remove from oven, brush with marmalade and place back in the oven for 10 to 15 minutes.