Due to the Duke of Edinburgh's absence from today's events, the Queen is being accompanied in the state limousine by one of her ladies in waiting, Diana Marion, The Lady Farnham.
In the carriage procession this afternoon, she will be joined by the Prince of Wales and Duchess of Cornwall.
Prince Phillip is being treated in hospital for a bladder infection.
An investigation has been launched into how unpaid workers bussed into London for the Diamond Jubilee celebrations were left stranded.
The Archbishop of Canterbury Rowan Williams spoke of the Queen's lifelong dedication to her people, her country and the commonwealth.
The Queen has a packed schedule on the final - and climactic - day of the Diamond Jubilee weekend.