Steep the tea bags in the boiling water for 5 minutes. Combine the sugar and fruit in a bowl. Remove the bags and pour the tea over the fruit and sugar. Allow to soak overnight.
The next day, preheat the oven to 150 C / Gas 2. Grease a 900g loaf tin and line with baking parchment. Drain the fruit.
Transfer the fruit into a large mixing bowl then mix in the marmalade, mixed peel, egg and flour. Spoon into the prepared loaf tin and smooth the top.
Bake in the preheated oven for 90 minutes to 2 hours, until a skewer inserted into the centre comes out clean. Remove from the oven and allow to cool fully before serving.