This is a Penny Red stamp of Great Britain, first issued between 1858 and 1879 as a successor to the famous Penny Black. It features the profile of Queen Victoria facing left, engraved by Charles Heath and based on the Wyon medal design.

Your example shows corner letters “A–F” which identify the stamp’s check positions on the printed sheet. The stamp is cancelled with a barred numeral obliterator, in this case “175”, which corresponds to the cancellation number assigned to Carlisle in Cumberland (now Cumbria), England. These barred numeral cancels are highly studied by collectors and can add postal history interest.

The Penny Red was printed in vast quantities, yet each plate and cancellation mark provides valuable insights for philatelists. Collectors often specialize by plating, cancellation numbers, or sheet positions, making even common-appearing issues quite significant within specialized collections.