Put the eggs, rum, orange juice, Madeira and treacle in a bowl and whisk together.
Put all the other ingredients in a very large bowl and stir well.
Add the egg mixture and stir again.
Cover with cling film and chill overnight.
The next day, place the chilled mixture into a buttered 1.2 litre pudding basin.
Cover and steam over a gentle heat for 6 hours.
Set aside until cold, then re-wrap the pudding in fresh greaseproof paper and foil.
Store in a cool place (not the fridge) for as long as possible (at least 2 weeks).
To serve, steam for a further 2 hours.