Flag used in the Saxon duchies in different states during different periodes between 1815-1918.
Flag of Saxe Coburg and Gotha between 1826-1911.
Flag of Saxe-Hildburghausen between 1815-1826.
Flag of Saxe-Meiningen between 1818-1918.

Flag of Saxe-Altenburg until 1893.
Own work
Sir Iain