The Queen's lifelong dedication to country and Commonwealth was praised today by the Archbishop of Canterbury at a Service of Thanksgiving for the Diamond Jubilee.
Dr. Rowan Williams paid tribute to The Queen's selfless devotion to others.
Dr. Williams told the congregation of leading figures from the UK and overseas that "our prayers and thoughts are very much with him this morning".
Dr. Williams said to those gathered: "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; she has responded with just the generosity St Paul speaks of in showing honour to countless local communities and individuals of every background and class and race.
"She has made her 'public' happy and all the signs are that she is herself happy, fulfilled and at home in these encounters.
"To declare a lifelong dedication is to take a huge risk, to embark on a costly venture. But it is also to respond to the promise of a vision that brings joy."
Due to the absence of The Duke of Edinburgh, who is being treated for a bladder infection in hospital, The Prince of Wales sat beside The Queen during the service.
Dr Williams highlighted how The Queen's commitment to others had brought her happiness: "But we are marking today the anniversary of one historic and very public act of dedication - a dedication that has endured faithfully, calmly and generously through most of the adult lives of most of us here.
"We are marking six decades of living proof that public service is possible and that it is a place where happiness can be found."
Many members of the Royal family attended the service including The Duchess of Cornwall, Duke and Duchess of Cambridge and Prince Harry.
It was announced today that The Queen will give a message of thanks for this weekend's Diamond Jubilee celebrations in a special address to be broadcast this evening.
The address, lasting just over two minutes, was recorded in the Presence Room in Buckingham Palace yesterday before the Jubilee Concert.
For the final day of the Diamond Jubilee weekend The Queen wore an Angela Kelly outfit of fine silk tulle, embroidered with tiny mint green star-shaped flowers embellished with silver thread.
It featured a mint green chiffon drape, scattered with Swarovski crystals on the shoulders.
The crown of the hat was covered in the same tulle and was also draped in mint green chiffon and Swarovski crystals.
The service featured the Diamond Choir, made up of children from across the UK, who sang Call Of Wisdom, an anthem by the British composer Will Todd.
Other music featured included the hymns All People That On Earth Do Dwell, arranged by Vaughan Williams; O Praise Ye The Lord, with music by Hubert Parry, a favourite of The Prince of Wales; and Guide Me, O Thou Great Redeemer.
Charities and organisations with royal connections were invited, including the Scout Association, which The Duchess of Cambridge joined earlier this year as a volunteer, and the Football Association, of which The Duke of Cambridge is President.
Children's charity Barnardo's, which has The Duchess of Cornwall as its President, was also represented, as was the British Council whose Patron is The Queen and Vice-Patron is The Prince of Wales.
Other groups invited included the Diplomatic Corps, Lord Lieutenants, the Duchy of Cornwall, the Duchy of Lancaster, the Royal Household and leaders from other faiths.
As The Queen left the cathedral cheers went up from the crowds lining the precinct of the historic building designed by Sir Christopher Wren.
With her lady in waiting she made the short journey by limousine to Mansion House for a reception where she will met members of the congregation.
Members of the family attended a Diamond Jubilee lunch at Westminster Hall, before returning to Buckingham Palace in a carriage procession.
The Queen, The Prince of Wales, The Duchess of Cornwall, The Duke and Duchess of Cambridge and Prince Harry appeared on the balcony at the Palace for a flypast by the Royal Air Force.
There was also a Feu de Joie - a celebratory cascade of rifle fire given as a salute by The Queen's Guard - interspersed with the National Anthem played by the Band of the Irish Guards.