Smiling broadly and waving to the jubilant throngs the Queen made the short journey from St Paul’s Cathedral cathedral to Mansion House.
Accompanied by her lady-in-waiting Diana Marion, The Lady Farnham, she was greeted by the Lord Mayor of London, David Wooton, and his wife before joining some 250 guests in the impressive Egyptian Hall.
Most of the congregation from St Paul’s were also invited, making up some of the 2,000 guests.
The guests of honour then left both receptions and were driven to Westminster Hall for a special Diamond Jubilee lunch.
A short distance away, a bigger reception took place in the Guildhall, one of London's most historic buildings, attended by Prince Charles, the Duchess of Cornwall, Prince Harry and the Duke and Duchess of Cambridge.
They made their entrance to a fanfare by the State Trumpeters of the Household Cavalry.
Underneath the impressive hammer beam roof, 700 lucky invitees awaited the arrival of royal family.
Guests feasted on a starter of marinated Uist Island salmon with Lyme Bay crab, followed by saddle of Welsh Cambrian Mountain lamb with braised shoulder of lamb, grilled Isle of Wight asparagus, Jersey Royal potatoes and Jubilee sauce.
The special menu paid tribute to the UK with a culinary tour of the British Isles.
Founded in 1978, it has a special meaning for the royal family - William and Harry's later mother, Diana, was a patron.
The Queen smiled warmly to the young members of the National Children's Orchestra - who performed later - before making her way to her table.
The National Children’s Orchestra finished off proceedings with a programme of music in honour of the Queen.
As she did so, other senior members of the royal family were seated around the splendid historical setting – the scene of Charles I's trial and also where the Queen Mother lay in state in 2002.Above them was the Diamond Jubilee stained glass window, presented as a gift to the Queen by members of both Houses of Parliament, before it is permanently installed above the north door.
The 'symphony of dessert' was chocolate delice, bread and butter pudding and berry compote with Sandringham apple sauce.