The Archbishop of Canterbury paid tribute to the Queen as she returned to Westminster Abbey for a service to mark the 60th anniversary of her coronation in 1953.
At Westminster Abbey, where the Queen was crowned on June 2 1953, Britain's leaders, royals and ordinary members of the public gathered to honour her.
Members of the Royal Family among the congregation of 2,000 included the Prince and the Duchess of Cornwall, the Duke and Duchess of Cambridge, Prince Harry, the Duke of York, Earl and Countess of Wessex, and the Princess Royal. Prime Minister David Cameron, Commonwealth Secretary General Kamalesh Sharma and senior individuals from the military were also among the guests.
The Duke of Edinburgh missed a royal engagement with the Queen last night but was by her side today. The service - which was divided into the Recognition, Anointing, Homage and Thanksgiving, reflecting parts of the original Coronation ceremony - is the main event to mark the historic event but it is a lower-key affair compared to last year's Diamond Jubilee celebrations.
The Archbishop of Canterbury paid tribute to the Queen's devotion to duty and told the congregation that they were celebrating "60 years of commitment".
"Today we celebrate 60 years since that moment, 60 years of commitment," said the Archbishop.
He went on to say: "A nation that crowns its head of state with such a model of liberty under authority expresses commitment to the same glorious values for itself."
The Archbishop singled out one element from the 1953 ceremony, telling the guests how the Queen was handed the sword of state.
He read some of the words from the coronation that described the role expected of the new monarch, who should use the sword to "do justice" and "help defend widows and orphans".
"The symbols and words point us to our deepest understanding of the nature of power, which is found neither in pomp and circumstance nor in public displays but in radical commitment, single-minded devotion and servant leadership," said the Archbishop.
Sitting with the Queen were senior royals the Prince of Wales, Duchess of Cornwall, Duke of Cambridge and his heavily pregnant wife Kate, and Prince Harry.
Prime Minister David Cameron took part in the service of celebration by giving one of two Bible readings. The other was delivered by Kamalesh Sharma, secretary general of the Commonwealth.
The abbey service was divided into the Recognition, Anointing, Homage and Thanksgiving, reflecting parts of the original coronation ceremony.
Artefacts associated with the ceremony including the majestic St Edward's Crown, used to crown new monarchs, also played an important part.
Poet Laureate Carol Ann Duffy wrote a poem for the service that focused on the emblem of kings and queens - the crown.
Duffy's short piece, read by actress Claire Skinner, represented the coronation's Homage element and concentrated on the burden and gift that the crown represents for the Queen - "one head alone can know its weight".
Music was an integral part of the Queen's crowning and for today's service the Thanksgiving was represented by the hymn Praise To The Lord, The Almighty, The King Of Creation.
The priceless St Edward's Crown - with which the Queen was crowned - was on display on the High Altar - the first time the heavy, solid gold, jewel encrusted crown has left the Tower of London since the 1953 coronation. Its transfer from the Tower to the Abbey came under tight security with the arrangements kept secret.
The Ampulla, the gold, eagle shaped bottle from which the holy oil was poured for the anointing - the most sacred part of the coronation - also stood on the altar. It has also moved from the Tower.
A flask of aromatic oil - taken from the same batch made for the Queen's coronation - was processed through the Abbey, carried by representatives of the people of the UK , to the Sacrarium, received by the Archbishop of Canterbury and placed by the Dean of Westminster on the High Altar.
After the ceremony the Queen and members of her family, who had attended the service, made the short journey to College Hall, the 14th century medieval Abbot's dining Hall, for lunch with the Dean and the Chapter of Westminster.
Among the 100 guests were Charles and the Duchess of Cornwall, the Duke of York, the Earl and Countess of Wessex, the Princess Royal and Vice Admiral Sir Tim Laurence.
The Queen was crowned at the Abbey on June 2, 1953 as a 27-year-old mother 16 months after her father King George VI died.
Additional reporting, PA
Video: The Coronation remembered