1881: Quetzal 20 c. yellow and green, used example, cancelled by the rarest of all cancellations of Guatemala, on this or any other issue, "AGENCIA POSTAL DE GUATEMALA / PANAMÁ" dated 1 May 1883 in purple and also a barred numeral "B16" arrival mark of Great Britain in black (Plymouth TPO), a great rarity, including this stamp only five recorded, two on cards and three on lose stamps
