Place all the dried fruit in a bowl. Add the orange rind and juice and sherry or brandy, and set aside to soak.
Grease a 1.4 litre pudding basin and place a disc of greaseproof paper on the bottom.
Beat together the margarine and sugar with an electric mixer until light and fluffy, then gradually beat in the eggs. Stir in the apple, carrot, almonds and soaked fruits. Sift over the flour and mixed spice, add the breadcrumbs and mix together.
Spoon the mixture into the pudding basin and smooth the top. Lay a doubled sheet of greaseproof paper and then of aluminium foil on top. Fold to make a pleat in the centre, then smooth down round the basin. Tie securely with string.
Bring a steamer or deep pan of water to the boil. Place the basin inside and steam for 3 hours, adding water as needed.
Remove the basin and take off the foil and paper. Cover with a tea-towel and cool completely. Wrap in fresh greaseproof paper and foil. Store in a cool, dark place for up to 3 months.
On the day of serving, steam the pudding for a further 1 1/2 hours. To make the sauce, blend the cornflour with 1/3 cup milk. Heat the remaining milk until almost boiling, then pour over the cornflour mixture, stirring. Return to the pan and stir over medium heat until thickened. Simmer for a further 1–2 minutes, still stirring. Add the sugar and brandy and stir to dissolve. Taste for sweetness, adding a little more sugar if necessary. Turn out the pudding onto a serving plate. Serve with the hot brandy sauce in a sauceboat or jug.