Great Britain. (Spain). 1857. Stamp-less envelope written from London dated '15th Aug 1857' addressed to Spain cancelled by 'London Paid' in red, rated '1s in top right with '2/2' rate m/s in red, endorsed 'per "Sultan" and sent direct by 'P & O' from Southampton, charged '4R' in blue with hand-struck 'MP' (Medio-Porte) in blue on reverse (showing the cover was allowed at Printed Matter rate) and Cadiz arrival '23rd Aug'. Very nice item with scarce Medio-Porte hand-struck mark.