The 2013 parade will commemorate a momentous year that saw London host the Olympic and Paralympic Games and the Queen's Diamond Jubilee.
Londoners are being warned that central London will be extremely busy throughout the Diamond Jubilee weekend.
Will cloud and rain take the shine off some of the pomp and pageantry?
The birthplace of the Queen is to be honoured with the Westminster City Council's 100th Green Plaque. Queen Elizabeth was born at Bruton Street in London in 1926. The building is now an office. The Green Plaque is one of the ways the local authority is marking Her Majesty's Diamond Jubilee.
The plaques recognise people who have made lasting contributions to society. The first one marked the life of Sir Winston Churchill. Other people whose lives have been highlighted by the honour, include Jane Austen, Oscar Wilde, Sir Arthur Conan Doyle, Edward Elgar, Jeremy Bentham and the Bee Gees.
One of the London's best-known landmarks is to be renamed in honour of the Queen's Diamond Jubilee, following a campaign by MPs.
The clock tower of the Palace of Westminster - known to millions by the name of the bell it houses, Big Ben - will in future be known formally as the Elizabeth Tower.
Commons authorities backed the change last night after dozens of politicians added their names to a push by Tory Tobias Ellwood in favour of the switch.
The former Deputy Prime Minister Lord Prescott has called for an investigation, after allegations that unpaid workers at the Diamond Jubilee river pageant were forced to sleep under London Bridge before they started their shift.
Lord Prescott says the workers were brought into the capital under the Government's Work Programme, where they worked as stewards controlling the crowds.
He claims it could set the tone for staffing London's Olympics.
Simon Harris has this report.
Olympic organisers have made a statement about their contract with Close Protection UK, after the company was accused of forcing unpaid Jubilee workers to sleep under London Bridge.
– London 2012 spokesperson
Close Protection UK is providing fire marshall services for us. They were appointed via competitive tender process, and will be providing accommodation for staff where necessary (ie where they don’t live locally). We take the welfare of workers very seriously, and we were assured during the tender process that appropriate accommodation will be provided.
Among the crowds on The Mall today there will have been many people claiming that they're the greatest royal fan. But that title must surely belong to Margaret Tyler who has the biggest collection of royal memorabilia in the country - more than 10,000 items.
London Tonight's Business Correspondent Glen Goodman reports:
Glen Goodman caught up with ultra-royalist Margaret Tyler on The Mall earlier, after she'd waved the Queen past in her limousine.
Clearly this year's royal occasion did not disappoint.
Margaret Tyler is so devoted to the British monarchy that she's even named her rooms after royal residences - Buckingham, Clarence, Balmoral, Windsor and Sandringham.
Now she is offering fellow royalists the chance to stay in the "Sandringham suite", as she explained to our correspondent Glen Goodman.
From the photos of her collection, it is clear just how devoted Margaret Tyler is to the Royal Family.
The long-standing monarchist from Wembley has extended her house to make room for her hoards of regal memorabilia.
One person who would never have dreamed of missing today's celebrations is Margaret Tyler from Wembley.
She has 10,000 pieces of royal memorabilia and says she will never stop collecting.
Glen Goodman was given the full tour earlier this week.