In a large mixing bowl, add breadcrumbs then pour melted butter over and mix to combine. Stir in sugar, golden syrup and essences. Set aside to cool a little before mixing in flour, salt and mixed fruit. Dissolve baking soda in milk, add to bowl and mix well to combine.
Transfer batter to a well-buttered or non-stick pudding basin. Cover basin with lid, well-buttered tinfoil or a pudding cloth tied securely in place.
Quarter-fill a large saucepan with water and bring to the boil. Carefully lower in basin then cover and steam for 2 hours. Check saucepan occasionally and top up with more boiling water if necessary. Turn pudding out and set aside until ready to serve.
To make rum sauce, in a small saucepan, heat first measure of cream until small bubbles appear.
In a bowl, whisk together egg yolks and sugar until creamy. Pour heated cream into egg mixture, whisking constantly. Return to saucepan and cook, stirring, over medium heat until mixture coats the back of a wooden spoon. Remove from heat and set aside to cool. Add rum, fold in whipped cream then transfer to a pouring jug.
Decorate pudding if desired. Pour warmed brandy over the top, set pudding alight and serve with rum sauce.