Isle of Man. (Great Britain). 1850. Pre stamp envelope written from Castletown dated 'June 21st 1850' addressed to Douglas cancelled by 'Castletown-Isle-of-Man' undated circle in blue, rated '1' in m/s and endorsed 'Paid' with 'Douglas-Isle-of-Man' receiver 'June 22' on face. The Castletown in blue is scarce.