P&O Cruises is a British/American cruise line based at Carnival House in Southampton, England, operated by Carnival UK and owned by Carnival Corporation & plc. Originally a constituent of the Peninsular and Oriental Stem Navigation Company, P&O Cruises is the oldest cruise line in the world, having operated the world's first passenger ships in the early 19th century. it is the sister company of, and retains strong links with, P&O Cruises Australia. P&O Cruises was de-merged from the P&O group on 2000, becoming a subsidiary of P&O Princess Cruises, which subsequently merged with Carnival Corporation in 2003, to form Carnival Corporation & plc. P&O Cruises currently operates eight cruise ships with a total passenger capacity of 14,970 and a 5% market share of all cruise lines worldwide. Its most recent vessel, MVBritannia, joined the fleet in March 2015.