ONDON — Several days of official celebrations marking the Queen's 80th birthday kicked off today with a nationally broadcast service at St. Paul's Cathedral and a banquet where the Queen delighted guests by poking fun at her age.

"As Groucho Marx once said `Anyone can get old — all you have to do is to live long enough,' " the Queen told diners at a banquet laid on by the Lord Mayor of London.

The Queen turned 80 on April 21, a day marked with a family party. Tradition provides an official birthday for the monarch on June 17, because the weather is generally better for public events.

The official birthday is marked each year with the Trooping the Colour, a military parade in central London, where the Queen takes the salute. A children's party, in the garden of Buckingham Palace, will be the final event of the birthday celebrations on June 25.

Religious and government leaders gathered in St. Paul's for the service of thanksgiving, while hundreds of people stood at barricades outside hoping for a photograph or a few words with the Queen.

"At the symbolic centre of our political life is a person," Archbishop of Canterbury Rowan Williams said in his sermon.

"There are risks to this. Your majesty has more reason than most to know the cost of a culture fanatically eager for gossip and trivia and the exposure in public of what should be private," Williams said.

But he went on to praise the Queen's witness of her Christian faith despite adversity.

"We have been able to see a bit more clearly the personal depth of our monarch's faith, more and more evident in successive broadcasts and testimonies," he said.

"And this means that at the hub of our political life is not only a person with whose vulnerability we can identify but a person visibly standing before God and God's judgment in humility and hope," Williams said.

About 40 members of the Royal Family — including the Queen's husband, Prince Philip, her heir, Prince Charles, and his sons, Prince William and Prince Harry — were among the 2,300 people at the service.

British Prime Minister Tony Blair was also on the guest list, as were former prime ministers Margaret Thatcher and John Major.

Several hundred people crowded barricades in front of St. Paul's, teetering on tiptoe and waving cellphone cameras in the sunshine. Children waved flags, and some admirers came prepared with ladders, lawn chairs, posters and small gifts.

Margaret Kittle, a Canadian tourist in London, said she hopes Canada never loses the monarchy.

"Would we like a president? Never, no we just want to keep a Queen forever and her heirs and successors," she told a reporter. ``We're very happy with her, we don't want to change at all, ever." Her hometown was not available.

"I just bought this thing," said John Lawrence, 48, pointing to a digital video recorder. "Got to see if it works — and what better way?"

"I spoke to her today, stood right next to her, and she was absolutely radiant — her smile, everything," said 71-year-old Terry Hutt, a former aide to the Queen's late mother.

Ronan O'Brien, 39, in a group of construction workers, brought a concrete-spattered ladder to help them see the spectacle. "Can't get enough of our monarch — we love her. Apart from her children, that is," O'Brien said.

Shirley Rose, 71, of Dallas, Texas, got a few words with the Queen. "I told her I was from Texas and that I'd come to wish her happy birthday. She stopped right away and said `thank you,' " Rose said.

Lord Mayor David Brewer was the host for a lunch for 350 guests, with a menu created by top British chefs who competed for the privilege on a popular television show.

The winning dishes include smoked salmon with blinis, pan-fried turbot, roe venison and custard tart.

"I count my blessings on my birthday. I am aware of the value of the advice and encouragement that I am lucky enough to receive from every quarter: from my family, from my friends, from all of you," the Queen said at the banquet.

"My Lord Mayor, I cannot do better than to use this wonderful occasion to express my heartfelt appreciation to the many, many thousands of people from this country and from overseas who have sent me letters, cards and messages of goodwill over the last couple of months."

ASSOCIATED PRESS

And apparently she cracked quite a few jokes in her little dinner speech.