Soak the fruit in the tea for at least 2 hours.
Place the flour in a large mixing bowl. Using your fingertips, rub in the butter until the mixture resembles breadcrumbs. Stir in the salt, mixed spice, caster sugar and yeast.
Make a well in the centre of the dry ingredients, add half the beaten egg and gradually add 150ml milk, adding a little more if needed, until a slightly sticky dough is made. Turn out onto a floured surface, adding more flour if it sticks, and knead for 8–10 minutes, until the dough is elastic and smooth.
Add the fruit and tea and knead well until combined, sprinkling in some more flour if the dough is too wet to knead. It should be smooth but still a little sticky.
Place in a clean, lightly oiled bowl, cover with oiled clingfilm and leave in a warm place until doubled in size (about 1½ hours).
Preheat the oven to 200°C, fan 180°C, gas 6. Knead the dough lightly and shape into a ball. Place on an oiled baking tray. Brush the top with the remaining beaten egg and bake in the oven for 45–50 minutes, until golden, covering with foil if it browns too quickly. The bread should sound hollow when tapped on the base. Remove from the tin to cool.