1.Preheat oven to 160°C/325°F. Grease a deep 22cm (9-inch) round cake pan; line base and side with baking paper.
2.Beat butter, rinds and sugar in a large bowl with an electric mixer until light and fluffy. Beat in eggs, one at a time. Fold in sifted flours and juices, in two batches; spread mixture into pan.
3.Bake cake 1 hour 10 minutes. Stand cake in pan 10 minutes before turning, top-side up, onto a wire rack to cool.
4.Meanwhile, make candied citrus, filling and glacé icing.
5.Split cake into two layers; sandwich with filling.
6.Drizzle cake with glacé icing. Just before serving, top with candied citrus.
candied citrus Combine sugar and the water in a large frying pan. Stir over low heat, without boiling, until sugar dissolves; add orange and lime slices. Bring to the boil. Reduce heat to low; simmer, uncovered, 15 minutes, turning slices occasionally. Remove from heat; cool slices on a wire rack. filling Beat ingredients in a small bowl with electric mixer until soft peaks form. glacé icing Sift icing sugar into heatproof bowl; add boiling water, stir until smooth. storage Cake will keep in an airtight container at room temperature for up to 4 days. Cake (without filling and glaze) is suitable to freeze. You will need about three oranges, one lemon and one lime for this cake.