in red ink and tied by "MOMBASA" single-ring d.s. and showing, on reverse, Aden transit c.d.s. and arrival c.d.s. The envelope a little soiled and with two vertical creases, though spectacular and very rare. Photo " /> <I> "B.E.A."</I> in red ink and tied by "MOMBASA" single-ring d.s. and showing, on reverse, Aden transit c.d.s. and arrival c.d.s. The envelope a little soiled and with two vertical creases, though spectacular and very rare. Photo | Christie's