The Queen officially named Cunard's 92,000-tonne Queen Elizabeth liner today - 72 years after watching her mother launch the first Queen Elizabeth.
As hundreds of invited guests listened to patriotic tunes including Land Of Hope And Glory in a quayside ceremony at Southampton, the Queen spoke the familiar vessel-launching words, requesting God to bless the vessel "and all who sail in her".
The naming, also shown in a live broadcast at Southampton's Guildhall Square, was completed as a jeroboam of 2009 Rothschild white wine - rather than champagne - was smashed against the bow of the ship.
Aged 12, the Queen was present on the Clyde in Scotland in 1938 as the then Queen Elizabeth - later the Queen Mother - launched the Queen Elizabeth.
Then, 29 years later and again on the Clyde, the Queen launched the QE2, which remained in Cunard service until just two years ago.
Today, the Queen arrived mid-afternoon in Southampton to tour the Italian-built third version of the Queen Elizabeth before the naming ceremony.
Accompanied by the new ship's Master, Captain Chris Wells, the Queen visited the bridge of the 964ft-long vessel, which can carry 2,068 passengers and 996 crew.
She also saw, for the first time, a portrait of her by 31-year-old Burnley-born artist Isobel Peachey, who is believed to be the youngest woman commissioned to paint the monarch.
The picture shows the Queen wearing a necklace and earrings - formerly belonging to Queen Victoria - which she wore at the Coronation in 1953.
The 16-deck ship, which can travel at a speed of around 27mph, also features an 18ft panel created by the Queen's nephew Viscount Linley, art deco interiors echoing the 1930s great age of ocean liners, and a shopping area featuring names such as Fortnum & Mason and Harris Tweed.
There is also an 832-seat theatre where passengers will be able to watch West End-style shows.
The ship leaves tomorrow on its maiden voyage - a 13-night sailing which includes stops at Lisbon, Tenerife and Madeira. Tickets for this first voyage went on sale on April 1 last year and were all snapped up within 30 minutes.
Fares for this first sailing ranged from £1,489 for an inside-facing room, to £15,799 per person for a grand suite.
The first world cruise starts on January 5, a 103-day trip which includes stops at 38 ports in 23 countries, including calls at Los Angeles, Sydney and Hong Kong.
Cunard president Peter Shanks said: "All of us at Cunard feel a great sense of pride in our new ship and today's ceremony. This pride stems from the continuation of our distinguished heritage and, of course, from the presence of Her Majesty the Queen."
At the naming ceremony, the hymn Jerusalem was sung by Alexander Howard-Williams and the other music included Handel's Zadok The Priest, Amazing Grace sung by Lesley Garrett, and also Land Of Hope And Glory.
Prayers were said by the Bishop of Winchester, the Rt Rev Michael Scott-Joynt, and a fanfare was played by the Irish Guards.
Also performing were the Coldstream Guards, the Band of the Scots Guards and the Bournemouth Symphony Orchestra.
Among those greeting the Queen on her arrival was the Lord-Lieutenant of Hampshire Dame Mary Fagan.
The Queen, who had flown into Southampton from Balmoral, sounded the ship's whistle during her tour.
She also met entertainment staff rehearsing in the theatre.
The Queen's last ceremony of this kind at Southampton was in 2004 when she named the Queen Mary 2 (QM2). She paid her last visit to the QE2 in Southampton in June 2008 - a few months before the vessel was sold to a Dubai property company.