The Queen has taken part in a service of thanksgiving at St Paul's Cathedral on the final day of her Diamond Jubilee celebrations.
The day will conclude with a glittering carriage procession, and RAF flypast.
The Queen's consort was absent from her side as she entered the cathedral; Prince Philip remains in hospital with a bladder infection.
In his sermon, the Archbishop of Canterbury paid tribute to the Queen's "lifelong dedication".
On Monday the Queen recorded a message of thanks for the nation's support ahead of a star-studded concert at Buckingham Palace.
The two-minute message, filmed in her private apartments at the palace, will be broadcast at 1800 BST on radio and television in the UK and across the Commonwealth.
Gun salute
Crowds cheered as the Queen and royal family members drove from Buckingham Palace for the service.
They started to build up in the early morning outside St Paul's and Buckingham Palace, which the Queen in her state Bentley, accompanied by one of her ladies in waiting, Diana Marion, The Lady Farnham.
There was a fanfare as the Queen, wearing an mint green outfit of fine silk tulle, embroidered with tiny star-shaped flowers, arrived at St Paul's for the service at 10:30 BST and the crowds chanted "God save the Queen".
Prince Charles, accompanied by the Duchess of Cornwall, the Duke and Duchess of Cambridge and Prince Harry, arrived a little before the Queen in a fleet of cars from Clarence House. The Princess Royal, the Duke of York and the Earl and Countess and Wessex were also in attendance.
Prime Minister David Cameron, who gave a reading, led the large representation from the government, military personnel and members of the royal household, at St Paul's alongside diplomats and foreign leaders.
In his sermon, the Archbishop of Canterbury praised the Queen for dedicating herself to the service of her nation and the Commonwealth.
Dr Rowan Williams told the congregation that the Queen's decision to devote her life to others has "endured faithfully, calmly and generously".
"I don't think it's at all fanciful to say that, in all her public engagements, our Queen has shown a quality of joy in the happiness of others," he added.
He also referred to Prince Philip in his address saying "our prayers and thoughts are very much with him this morning".
After the service, the Queen moved on to a reception at Mansion House - the official residence of the Lord Mayor of London. The Prince of Wales and Duchess of Cornwall are attending a similar event at the Guildhall.
A City of London Livery companies lunch at Westminster Hall will follow where guests will dine on salmon, followed by Welsh lamb, grilled Isle of Wight asparagus, Jersey Royal potatoes and chocolate delice, bread and butter pudding and berry compote with apple sauce.
The Queen and royals, including Prince Charles, the Duchess of Cornwall, the Duke and Duchess of Cambridge, and Prince Harry, will then take part in a carriage procession through Whitehall.
Personnel from all three armed services will line the streets for the procession, and the King's Troop will fire a 60-gun salute.
As the procession arrives in the forecourt of Buckingham Palace, there will be a guard of honour. The royals will then gather on the balcony to watch a flypast of World War II aircraft and a display by the Red Arrows.
Forecasters say the weather in central London will be cloudy and dry at first, with a top temperature of 14C, but there may be outbreaks of rain in the afternoon.
Prince Philip, 90, will remain under observation at King Edward VII Hospital in London, where he was taken on Monday as a "precautionary measure".
In December, he was treated at Papworth Hospital in Cambridge for a blocked coronary artery.
At the concert on Monday night, attended by 12,000 people, Charles paid tribute to his mother, describing her as "mummy" and a "very special person".
But he added there was a disappointing edge to the night. "The only sad thing about this evening is that my father couldn't be with us because, unfortunately, he was taken ill," he said.
Performers included Kylie Minogue, Robbie Williams, Sir Elton John, Shirley Bassey, Jessie J, Sir Tom Jones, Madness, Stevie Wonder and Sir Cliff Richard. The concert was brought to a close by Sir Paul McCartney with a rendition of Live and Let Die, complete with fireworks and pyrotechnics.
After the show, the Queen came on to the stage accompanied by Prince Charles and Take That star Gary Barlow, who helped organise much of the concert, to press a diamond-shaped crystal into a pod, igniting a beacon in The Mall to mark her 60 years on the throne. It was one of more than 4,000 lit across the UK and the Commonwealth.
-BBC
