Preheat the oven to 180C/350F/gas mark 4
Use a 450g/1 lb loaf tin.
Grease and line the tin. Sift the flour, salt, cinnamon and baking powder. Rub in the butter until the mixture resembles fine breadcrumbs. Mix in the sugar, vanilla, sour cream and the buttermilk. Pour into the tin and bake for 45 minutes. Leave to firm up for ten minutes before turning out onto a wire rack.
