A letter cover featuring a rare Bermuda stamp dating back more than 150 years has sold at auction for just less than $20,000.

The cover was one of several items featured at the Philatelic Collectors Series sale this week at the Spinks Auction House in London. Described by the auction house as an “incredible rarity”, bidding reached on the stamp closed at £14,000.

The American-styled date stamp, which read “Paid at Ireland Island/Bermuda”, was found on a mourning envelope from Midshipman John Hemery Robinson to his mother in New Brunswick dated January 22, 1863.

Midshipman Robinson died at the age of 25 in late 1870 while serving on board the HMS Endymion, and was buried in the Sea of Japan.

A description of the item by the auction house said: “This item shows a fine strike of the previously unrecorded American-style 32mm ‘Paid at Ireland Island/Bermuda’ circular date stamp and with locally made handstruck ‘6d’, the latest recorded date of use, at upper right, both struck in red. A remarkable cover only discovered in among an original family correspondence in the mid-1990s.

“In 2000, Geoffrey Osborn provided evidence confirming the purchase of an Ireland Island Paid date stamp in records for the year ending October 1863, the cost of the instrument being £1/19/6d.”

Research has suggested that the stamp used on the cover was obtained from an American source by the Bermuda postmaster-general for use at Ireland Island.

Bermuda was one of the first jurisdictions in the world to introduce a uniform postal rate in 1842, only two years behind Britain and three years ahead of America.

The earliest Bermuda stamps, Perot stamps, were named after William Bennett Perot, who served as Bermuda’s first postmaster-general from 1818 to 1862.

Only 11 Perot stamps are known to still exist, and they can fetch more than $100,000 at auction.