Roughly chop figs, then soak in hot water for 2–3 minutes. Drain thoroughly. Spread out in a single layer on a dish towel; pat dry and allow to cool.
Chop cooled figs into tiny pieces. In a small bowl, mix together chopped figs, orange zest, and ¼ teaspoon ground mixed spice. Set aside.
Heat oven to 350°F. Line two baking sheets with parchment paper.
Sift flour and remaining ¼ teaspoon ground mixed spice into a large bowl.
Add cold, cubed butter to flour mixture, tossing around gently to coat. With pastry blender in one hand, cut in butter while rotating bowl in quarter-turns with your other hand. Stop once the mixture looks like fine breadcrumbs.
Stir in caster sugar and salt. Mix in milk a little at a time until dough starts to come together. (Ditch the spatula and get in there and mix with your hands, if necessary to fully incorporate the milk.)
Turn dough out onto a lightly floured surface. Knead for a moment until you have a smooth, firm dough.
Divide dough into 4 equal pieces. Roll each piece out into a 6" circle. NOTE: If at any point during the next several steps the dough starts to become sticky and misbehave, put it in the fridge for 10–15 minutes.
Sprinkle fig mixture evenly over two of the dough circles. Top with remaining two circles. Then roll each dough-n-fig stack into a 10" circle.
Crimp edges with tines of a fork. Cut each circle into 12 equal triangles. Place triangles (petticoat tails) onto prepared baking sheets. Brush petticoat tails with cream, then sprinkle with granulated sugar.
Bake for 15–17 minutes or until golden at the edges.
Transfer biscuits to wire rack and allow to cool completely.