Preheat oven to 180 degrees. Grease and line a 20cm round tin with baking paper. Beat butter, sugar and lime rind until pale and creamy. Add eggs one at a time, beating between each addition. Fold in yoghurt, flour and coconut in
alternate batches until just combined. (Mixture is quite dense). Spoon into cake tin and bake for 1 hour. Place icing sugar in a medium sized bowl and stir through lime juice to make a runny paste. Drizzle over cooled cake and top with coconut flakes.