Preheat the oven to 180C/350F/gas mark 4
Use a 450g/1 lb loaf tin.
Grease the loaf tin. Sift together the flour, salt, ginger and baking powder. Rub in the butter until the mixture resembles fine breadcrumbs. Mix in the sugar, walnuts and crystallised ginger. Mix most of the sour cream with the milk and add to flour and butter. Beat thoroughly. This makes a very sticky dough. Turn into the loaf tin. Brush the top with remaining sour cream and sprinkle with demerara sugar. Bake for 1 hour 5 minutes, until the teabread is golden brown and sounds hollow when tapped underneath. Serve sliced and buttered.
