Yes, you are right, it is not a Paquebot Cancellation! But this cover illusrates a Ship Letter/ Paquebot mark as old as Methuselah! This letter has been mailed at Calcutta on the 26th of November 1850 and arrived Port Louis, Mauritius 0n 26th of December 1850 where the Ship Letter mark was applied – perhaps the first year of usage! The picture 2849 (B) shows a letter with the same mark but 124 years later in nearly unchanged quality! Kudos!!!
Collection Capt. Schulz