Porter is a type of dark Irish beer, not now as widely available as it once was. It is not as strong as stout but Guinness, Murphy's or other Irish stout can be substituted in this recipe if mixed fifty-fifty with water. This cake is quickly and easily made and, though it tastes good fresh from the oven, it is best kept for about a week in an airtight tin.
Melt the butter and sugar in the porter in a saucepan. Add the fruit and simmer for 10 minutes. Allow to go cold and add the sieved flour, baking soda, spices and lemon rind. Beat the eggs and mix in with a wooden spoon. Pour into a greased and lined 9 inch/ 25 cm cake tin and bake on the middle shelf of a pre-heated oven at gas mark 3, 325°F, 160°C for about 1 3/4 hours. To test the cake, push a skewer into the centre; if ready, the skewer will come out clean. Allow the cake to cool in the tin.