Combine butter, sugar, milk, fruit and rind in a large saucepan and bring to the boil. Remove from the heat and stir in bicarbonate of soda. Sift in the flour, cinnamon and salt and mix gently until blended.
Pour into prepared pudding basin and cover with a double layer of greased baking paper. Secure lid or cover with a layer of foil and tie a double piece of kitchen string around the basin to secure.
Place into a large deep saucepan with boiling water coming halfway up the sides of basin. Boil for 2 hours, replenishing water as necessary. Stand in basin for 10 minutes before turning out on to serving plate.