Heat the oven at 180 C(160 fan) 350 F, Gas 4.
Oil two baking trays.
Cream the margarine, butter and sugar until light, then beat in the orange rind.
Stir in the oats, flour and mixed spice to make smooth pliable dough. Roll out to approx 3mm thick.
Cut into rounds and prick twice in the centre of each round. The mixture should make around 18 biscuits.
Bake for 12 to 15 minutes until golden.
Cool a little on the trays, then either dust with caster sugar while warm and move to a wire tray, or melt some chocolate and pipe over the top, or dip into melted chocolate.