In a large mixing bowl, combine the sultanas, chopped prunes, candied citrus, and candied fruit mix. Cut the glacé cherries in half and add to the mixing bowl. Peel and grate the apple and carrot and add to the fruit mixture. Add the zest and juice of one orange along with the brandy and stir the mixture together well. Cover and set aside for at least 1 hour. The fruit can be left in the fridge overnight.
To prepare the pudding basin, cut a small circle of parchment paper that will fit inside the bottom of the basin. Spray the basin well with non-stick spray. Place the parchment circle on the bottom of the basin and spray again. Set aside. Cut another large circle of parchment paper that will cover the top of the bowl and set aside.
In a small mixing bowl, combine the flour, baking powder, baking soda, salt, and spices. Whisk together and then set aside.
In a large mixing bowl, combine the softened butter and brown sugar. Beat until blended - the mixture will appear crumbly. Add the egg and beat until smooth and creamy. Add the fruit mixture along with any juices. Fold together with a spatula until well mixed.
Add the dry ingredients and stir together until smooth. Spoon the pudding batter into the basin and smooth the top. Place the parchment circle over the top of the pudding basin and cover with a large piece of foil. Press the foil tightly around the edges. Use a piece of string to tie the foil tightly around the pudding basin. It should be as airtight as possible.
Fill a large pot of water with several inches of water. If the bowl you are using has a flat bottom then place a canning lid or even a little ring of folded aluminum foil under the bowl so that it isn't resting completely on the bottom. Add the pudding basin and enough water so that it comes two thirds up the side.
Place over medium heat and cover with a lid. Bring the water to a gentle simmer and then turn down the heat. Keep the water at a gentle simmer for 3 1/2 to 4 hours. Check occasionally that the water level hasn't gone down too far, adding more if needed.
Check that the plum pudding is done by inserting a thermometer through the foil top and into the middle of the pudding. The temperature should register around 200°F. Remove the pudding basin from the pot and set aside to cool for 5 minutes. Do not let it cool completely in the basin or it may become hard to remove.
Cut the string and remove the foil and parchment top. Use a spatula to gently run around the edge of the pudding and loosen it from the bowl. Pace a serving plate upside-down over the basin. Carefully flip the plate and basin over together. Gentle shake the basin, the pudding should fall onto the serving plate. Remove the small piece of parchment on the top of the pudding.
While the pudding is steaming, make the brandy butter sauce. In a small saucepan, melt the butter over medium high heat. Add the sugar and whisk together. This mixture will look gritty which is normal. Add the heavy cream and whisk together. Bring the sauce up to a boil, whisking regularly.
Remove from the heat and add the brandy. Set aside until serving. The sauce can be made ahead and stored in the fridge. It will harden when chills but can be reheated before serving. If you find that butter separating out a bit from the sauce, add a splash of heavy cream and whisk it back together.
To flame the pudding with brandy, make sure that the pudding is on a heatproof platter. Add the brandy to a stainless steel ladle. Gently warm the ladle with brandy over a gas burner. If you don't have a gas burner, you can warm the brandy in a small saucepan and carefully pour it into the ladle. Use a lighter to ignite the warm brandy in the ladle and drizzle it slowly over the pudding. Allow the flames to burn out.
Dust the pudding with icing sugar if desired and serve the plum pudding with the brandy butter sauce. Enjoy!