Mix together 2 teaspoons sugar, 125ml water, yeast, milk and 125g flour.
Cover and allow to sit for 30 mins until bubbly.
In a large bowl beat the eggs, salt and 200g caster sugar until light and fluffy.
Stir in the melted butter and orange zest.
Stir in the yeast mix.
Mix in the flour.
Knead in the bowl for about 10 minutes, then knead in the raisins (if using).
Cover and let rise in a warm place until doubled in volume.
Knead dough for a couple of minutes then let it rise again.
Grease mould.
Fill the prepared mould about 1/3 full and let rise until the dough is even with the rim.
Preheat the oven to 200 C / Gas 6.
Bake for 15 minutes in the preheated oven, then turn down the temperature to 180 C / Gas 4. Continue baking the bread for another 40 minutes.
Cool.