Queen Mary 2, Queen Victoria and Queen Elizabeth arrived in the city just after dawn, escorted in by a fire tug and a flotilla of small boats. Crewmembers gathered on deck for a big cheer and the ships' whistles echoed across the docks as Queen Victoria and Queen Elizabeth positioned next to Southampton's City Terminal, bow to bow, while flagship Queen Mary 2, sporting a huge banner saying ‘Congratulations Ma'am', passed each ship in turn to create a photo-opportunity of the three together.
The celebrations carry on later tonight with an aerial display over Southampton Docks by the Red Arrows and a grand finale of fireworks. If you're coming to watch, here's our guide to the order of events, including how to access Cunard's one-day-only radio broadcast, Cunard FM, and the festival in Mayflower Park.
We'll be reporting from the ships later today so follow our Facebook and Twitter pages for all the news.
--by Sue Bryant, Cruise Critic Contributing Editor