The importance of Southampton to the cruise industry was indicated by P&O Cruises's 175th anniversary celebrations, which included all seven of the company's liners visiting Southampton in a single day. Adonia, Arcadia, Aurora, Azura, Oceana, Oriana and Ventura all left the city in a procession on 3 July 2012.

What cruise line celebrated a landmark anniversary in Southampton in July of 2012?