Preheat the oven to 180C/350F/gas mark 4
Use a 20cm/8 inch round cake tin.
Cut the squeezed orange into pieces, place in a blender and reduce to a pulp. Scrape into a bowl. Now blend the currants, and then the nuts, and add both to the bowl. Mix them thoroughly.
Mix the flour, bicarb, baking powder and the sugar (reserve 2 tbs.) together in a large bowl. Add the butter and three quarters of the milk and work together for about 2 minutes or until light and smooth. Add the remaining milk, yoghurt and cinnamon. Beat for a further 2 minutes. Stir in the orange-nut mixture until evenly distributed.
Grease and flour the cake tin and pour in the mixture. Bake for about 50 minutes. Remove from the oven and immediately pour over the mixed orange and lemon juices. Mix the remaining sugar with the cinnamon and sprinkle it over the surface. Leave until cold before serving.
