In a large bowl, mix together the breadcrumbs, flour and suet.
Add the raisins, making sure there are none stuck together. When these ingredients are well mixed, add the salt, nutmeg, ginger, mace, candied peel and orange zest and, again, mix thoroughly. Now, in a small bowl, beat the eggs well and add them and the brandy to the mixture and stir for at least 5 minutes to amalgamate everything thoroughly and evenly. Pack the pudding basin with the mixture, and cover with the foil, making a pleat in the centre. Then pull it down the outside of the basin and tie down with string, taking it over the top and tying it on the other side to make yourself a handle for lifting. Trim off the excess foil all the way round. Now steam the pudding for 4 hours, making sure that the saucepan doesn't boil dry.
Meanwhile, to make the sauce, begin by simmering the orange zest, 5 fl oz (150 ml) water and the sugar in a saucepan for 15 minutes until syrupy.Now mix the butter into the flour and divide it up into about 6 pieces, adding them to the syrup at the end of the cooking time, followed by the port, nutmeg and orange juice. Simmer the mixture for 1 minute over a gentle heat, stirring continuously, then serve immediately. When ready to serve, loosen the pudding all round the sides with a palette knife and turn out on to a heated dish. Serve with the port wine sauce.
Note: The sauce can be prepared in advance, except for the butter and flour part, which should be added just before serving.