Revellers will take to one of London's most famous thoroughfares for a street party to celebrate the Queen's 90th birthday.
The Queen's grandson Peter Phillips has masterminded the Patron's Lunch, an open-air party being staged in The Mall on Sunday, for 10,000 people, to mark the monarch's patronage of more than 600 charities and organisations.
It will bring to a close this weekend's events marking the Queen's anniversary that has already seen a St Paul's Cathedral thanksgiving service and a traditional Trooping the Colour ceremony.
The Queen, Prince Philip, Prince William and Prince Harry will join the revellers for part of the celebration with William and Harry expected publicly to praise their grandmother.
But the event could be disrupted by the British summer as the Met Office has issued a yellow rain warning for parts of the country including London with heavy showers forecast.
Tickets for the event were priced at STG150 ($A291) with the majority going to organisations or charities that have the Queen as patron and the remainder sold to the general public.
Enthusiastic crowds cheer as Britain's Queen Elizabeth II and the Duke of Edinburgh, pass by to view the Trooping the Colour ceremony. Source: AAP
