Preheat oven to 160 C, then line several baking trays with baking parchment.
Sift together the flour, salt, sugar, ginger and baking soda into a large mixing bowl.
Heat the butter and golden syrup together in a saucepan over a very low heat until the butter has melted. Remove the pan from the heat and leave to cool slightly, then pour it onto the dry ingredients.
Add the egg and orange rind and mix thoroughly to form a dough. Using your hands, carefully shape the dough into 30 even size balls.
Place the balls well apart on the prepared trays, then flatten them slightly with your fingers.
Bake for 15020 minutes, then carefully transfer the biscuits to a wire rack to cool.