Preheat your oven to 160°C (320°F). Grease and line a large loaf tin with parchment paper.
In a large bowl, combine the golden raisins, currants, and raisins. Pour the strong black tea over the fruits and let them soak for at least 30 minutes. This helps the fruits swell and soak up the tea’s flavor.
In another bowl, whisk together the whole wheat flour, baking powder, and salt. This ensures your cake rises evenly.
In a third bowl, beat the eggs with the light muscovado sugar until the mixture is smooth and slightly creamy.
Drain the soaked fruits, but keep the tea aside. Add the dry flour mixture to the egg and sugar mix. Stir gently to combine.
Fold the soaked fruits into the batter. Add about half a cup of the reserved tea to loosen the batter slightly. The batter should be thick but pourable.
Pour the batter into your prepared loaf tin and smooth the surface with a spatula.
Bake for 1 hour to 1 hour 10 minutes. Check for doneness by inserting a skewer or toothpick in the center; it should come out clean.
Let the cake cool in the tin for about 15 minutes before transferring it to a wire rack to cool completely.