cover 1891 2a. blue registered stationery envelope (opened-out) to Vienna additionally franked by 3a, cancelled "B" in bars (K12.) and showing small "REG" c.d.s. (R5.) on reverse, also 1906 2a. grey registered stationery envelope to London cancelled by "REG" c.d.s. (R7.) additionally franked by K.E. VII 1a. cancelled "B" in bars (K12.); a few minor faults. Rare usages of registered stationery in Aden. Photo