[3] It incorporates a tower with a ring of five bells, 19th- and 20th-century stained glass windows, and a two-manual pipe organ built in Ireland.[1] The cathedral is in possession of the Garter banner of Lord Shackleton, which hung in St George's Chapel, Windsor Castle, during his lifetime.[5] On the south wall of the cathedral is a White Ensign flown during the Battle of the River Plate by HMS Achilles.A wooden plaque below the flag has the inscription: "One of the ensigns worn by HMS Achilles at the Battle of the River Plate 13th December 1939".[6] In the front of the building is a whalebone arch monument, made from the jaws of two blue whales, erected in 1933 to commemorate the centenary of British rule in the Falkland Islands.