Preheat the oven to 180C/350F/gas mark 4
Use a 450g/1 lb loaf tin.
Beat together butter, sour cream and sugar until fluffy. Stir in rind. Sift together flour and salt and add to the butter mixture. Add the milk, a little at a time. Stir in nuts and pour into the greased loaf tin. Bake for about an hour, until the cake rises and the top is firm and browned. Remove from the tin to a cooling rack.
Glaze: Stir the ingredients together over a medium heat until the sugar has melted, then pour over cake, decorating top with walnut halves. Cool completely before storing.
