This isn't exactly the same either, but it's the 'official' Guinness Cake recipe (taken from
http://www.guinness.com/ )
Ingredients (Serves 6)
* 8oz butter
* 8 oz soft brown sugar
* 4 eggs (lightly beaten)
* 10oz plain flour and 2 level tsps of mixed spice sieved together
* 8oz seedless raisins
* 8oz sultanas
* 4oz mixed peel
* 8-12tsps of GUINNESS® Draught
* 4oz walnuts
Cream butter and sugar together until light and creamy. Gradually beat in eggs. Fold in the flour and mixed spice. Then add the raisins, sultanas, mixed peel and walnuts. Mix well together. Stir 4tbps of GUINNESS® into the mixture. Mix to a soft dropping consistency. Turn into a prepared 7 inch cake tin. Bake in a very moderate oven, Gas mark 3 / 300° F for 1 hour. Then reduce and cook for another one and a half hours. Allow it to become cool. Remove from cake tin. Prick the base of the cake with a skewer and spoon over the remaining 4-8 tsps of GUINNESS®. Keep the cake for 1 week before eating.
Chris