In the same saucepan, combine the citrus peels, citrus flesh, orange juice, sugar and cranberries. Bring to a boil, reduce the heat to medium and simmer for 1 hour, stirring frequently, until the mixture is translucent. To check whether the marmalade is done, do a plate test (see note) or set a candy thermometer in the centre of the saucepan and simmer until it reads 104°C (219°F). During cooking, carefully skim off any foam.