The world's biggest liner, the 150,000-ton Queen Mary 2, was launched on a tidal wave of royal celebrations in Southampton.

It was a day the city will never forget, as history was made by the Queen when she officially named QM2, the supership of the 21st century.

Never before has Southampton seen such a vessel - not even the famous great liners of the past can compare in sheer size, scale and power of this new monarch of the seas.

And the city has never played host to such a lavish and breathtaking naming ceremony.

There was a gasp from the quayside audience when singer Heather Small finished her rousing song Proud and the huge backdrop of the purpose- built auditorium was dropped to reveal the striking bow and massive super- structure of the mega-liner.

Fireworks soared into the late afternoon sky high over QM2 - a sound and light display dazzled and danced against the ship and a blizzard of gold and red confetti cascaded over guests.

Former Queen's piper Jim Motherwell cut a dramatic figure as he played his bagpipes high on the ship heralding a spine-tingling performance by opera star Lesley Garrett singing Amazing Grace.

Sitting in the audience was Deputy Prime Minister John Prescott who before entering politics worked as a steward with Cunard. Transport Secretary Alistair Darling was also there, as well as celebrities including football manager Sir Bobby Robson, Sir David Frost and Sir Jimmy Savile.

Saints boss Gordon Strachan and his wife Lesley chatted happily with the Newcastle manager and were later joined by TV-am presenter Lorraine Kelly and former BBC royal correspondent Jennie Bond.

Performing the prayers of blessing, the Right Rev Michael Scott-Joynt, Bishop of Winchester, included a eulogy delivered in French to the families of those who lost their lives in the tragic accident in St Nazaire.

Just minutes before the event began QM2's owners Cunard announced that the ship was an even bigger record breaker than first estimated as the final survey showed her tonnage was in fact 151,400 tons.

Hailed as the longest, widest, tallest and costing £550m, the most expensive passenger ship ever, she has already become one of the most outstanding engineering projects of the new millennium.

In a repeat of 37 years ago when she named Southampton's legendary Queen Elizabeth 2 on Clydebank, the Queen pressed a button, to send a bottle of champagne crashing on to the ship's hull after saying the famous words: "I name this ship Queen Mary 2. May God bless her and all who sail in her."

As QM2's whistle blared - proclaiming her the queen of the oceans, the floor of the auditorium shook with the force. It was the original whistle from the liner Queen Mary that first sounded in the city back in 1936.

Earlier the Queen still walking with a stick following the operation on her knee, arrived by car at the city's eastern docks where she was met by QM2's master, Commodore Ronald Warwick, and Cunard President Pamela Conover.

Stevedores Nigel Graham and John Garner, with many years' experience between them, were introduced to the Queen and Southampton mayor Councillor Parvin Damani welcomed the cerise-clad monarch to the city.

During the ceremony Ms Conover told guests: "QM2 is a transatlantic liner with all the dignity and grace of the liners of the past, but she is also a transatlantic liner of the future.

"This is Southampton's ship and it renews the bond between Cunard and the city which began over 80 years ago."