The Queen's Diamond Jubilee celebrations culminated today in London with a service of thanksgiving at St. Paul's Cathedral followed by an appearance of Queen Elizabeth and members of the Royal Family on a balcony at Buckingham Palace as thousands of well-wishers cheered in the Mall below.

The Queen stood before the adoring throng, smiling and waving for more than 10 minutes. At her right hand was her heir Prince Charles and his wife, Camilla, Duchess of Cornwall, and at the Queen's left were her grandson Prince William, his wife Kate Middleton, Duchess of Cambridge, and William's younger brother Prince Harry.

Missing was the Queen's husband, Prince Philip, 90, who had been scheduled to be at her side but was taken to hospital Monday with a bladder infection and was unable to attend. He celebrates his 91st birthday on Sunday.

The Royal Air Force staged a spectacular flypast, featuring four Spitfires, one Hurricane and the RAF's aerobatic Red Arrows. The Irish Guard band performed and offered a rousing cheer for the Sovereign.

Earlier, Queen Elizabeth departed Westminster, where she was honoured at a luncheon, in a horse-drawn, 1902 State Landau carriage, open to the grey skies and a few drops of rain, heading back to Buckingham Palace.

Military bands and troops from the three military services lined the procession route. The Sovereign's Escort of colourfully uniformed mounted troops trotted ahead of, behind and alongside the coach.

In the coach with Queen Elizabeth were Prince Charles, wearing a top hat, and The Royal Family, who all assembled on the balcony at the palace for further ceremonies as crowds below cheered their appreciation for the Queen for her years of public service.

Scores of dignitaries on hand

Earlier Tuesday, St. Paul's Cathedral was filled with invited dignitaries and members of the extended Royal Family for the service of thanksgiving. Dignitaries include Prime Minister David Cameron and Deputy Prime Minister Nick Clegg, along with scores of other political figures.

The Queen rode to the church accompanied by a lady in waiting, Lady Farnham, standing in for Prince Philip.

The Queen walked alone into the church as crowds cheered outside. Within, a flourish of trumpets and a choir rose to greet her. Princes Charles, Harry and William stood with her just inside the entrance.

In his homily, Rowan Williams, the Archbishop of Canterbury, cited St. Paul's biblical directives toward selflessness and sacrifice.

"In all her public engagements, our Queen has shown a quality of joy in the happiness of others," he said.

"We are marking six decades of living proof that public service is possible and that it is a place where happiness can be found."

Queen Elizabeth has made others happy in her long reign, and by all appearances takes joy in the joy other others, Willliams said. The same, he added, can be said of Prince Philip. A chair was left poignantly vacant for him at St. Paul's.

"Our prayers and thoughts are very much with him this morning," the archbishop said.

After the church service, Queen Elizabeth exited the church accompanied by the Dean of St. Paul's, David Ison. She left by limousine, headed for a reception at Mansion House, residence of the Lord Mayor of London, David Wootton, where she was joined by about 250 guests and a children's choir. She then moved on by limousine through cheering crowds lining the streets to a luncheon at Westminster Hall.

Then came the carriage procession back to Buckingham Palace.

Queen to address Commonwealth

She made a rare address to the nation later on Tuesday, saying the events to mark her Diamond Jubilee "have been a humbling experience.

"It has touched me deeply to see so many families, neighbours and friends celebrating together in such a happy atmosphere," she said. "I hope that memories of all this year's happy events will brighten our lives for many years to come."

The Queen also thanked everyone who was involved with planning the activities commemorating her 60-year reign.

The broadcast at 1 p.m. ET followed a schedule that included the service at St. Paul's, a lunch in a medieval hall and a carriage procession back to Buckingham Palace, where the Queen and her family greeted well-wishers from the central balcony.

The two-minute address, recorded on Monday, is also available on the Royal Channel on YouTube, the palace said. Other than the annual Christmas Day broadcasts, the 86-year-old monarch has rarely spoken directly to the nation.

Prince William, left, and Kate, Duchess of Cambridge, arrive for a service of thanksgiving to celebrate Queen Elizabeth's 60-year reign during Diamond Jubilee celebrations in St Paul's Cathedral Tuesday. (Tim Hales/Associated Press)

The procession ended four days of celebrations, which included a jubilee concert Monday night outside the palace and a gathering of an estimated 1.25 million people to witness a flotilla of 1,000 vessels for a water pageant on the Thames on Sunday.

Festivities officially began Saturday with a 41-gun salute fired by the King's Troop, Royal Horse Artillery at Horse Guards Parade in central London, after which the Queen and husband Prince Philip attended the Epsom Derby, the U.K.'s richest horse race.

From Canada, Prime Minister Stephen Harper , Governor General David Johnston and Heritage Minister James Moore were in London for the four-day celebration.

Moore said it was an honour to be there. "I have been impressed by how many Canadians are here to celebrate Queen Elizabeth II's grace, leadership and remarkable public service," he said.

Harper has kept a relatively low profile in London. Later Tuesday, the prime minister was to announce the table tennis players who will represent Canada at the coming London Olympic Games.

Harper was also scheduled to join British Prime Minister David Cameron for a private dinner at 10 Downing Street. On Wednesday, the prime minister has an audience with the Queen.

With files from The Associated Press and The Canadian Press