Argentina. (British Post Offices). 1871. Stamp-less envelope written from Buenos Aires dated '16th Dec 1871' addressed to Italy cancelled by British Post Office 'Buenos Aires' on reverse, endorsed 'per Vapour "Onnia", routed via London, underpaid with Italy postage due Yvert 10, 50c orange and carmine and Yvert 12, 11 blue applied and tied by Genova date stamp and rated '15' in m/s. Very fine.