The Queen starts her Diamond Jubilee celebrations in earnest today with a traditional visit to the Epsom Derby.
Her Majesty will watch thoroughbreds race at the event on Saturday, which has had a long history, having first been run in 1780 and is flat racing's equivalent to the Aintree Grand National.
Queen Elizabeth II has had 10 runners in the Derby, the first in 1953 and the latest was in 2011 when Carlton House finished 3rd.
It is a fitting way for the Queen to start the four-day long celebrations as she is a passionate horse breeder and racer.
Around 130,000 punters will be eagerly awaiting her arrival at the racecourse which has sold out all its main stands.
Taking her place in the royal box the Queen will study the form and keenly watch the races - but will not bet a penny as she does not gamble.
Unlike last year's race the Queen does not have a horse entered in the Derby, or the other six featured races.
But she will be presenting the winning prizes in the renamed Diamond Jubilee Coronation Cup.
On Friday the Royal Navy warship HMS Diamond signalled the opening of the four-day Bank Holiday Diamond Jubilee festivities in dramatic fashion by firing a 21-gun salute that boomed across Portsmouth Harbour.
Hundreds of well-wishers lined the walls of Portsmouth Harbour and waved flags and cheered as the Type 45 destroyer arrived into its home base.
Up to a million people are expected to line the banks of the River Thames and nearby open spaces to watch a 1,000-strong flotilla sail through London on Sunday.
The Royal barge will be decked out with nearly 10,000 flowers and 600 plants, made up of 4,000 red carnations, 2,100 Darcey roses, 1,000 Patience roses and 500 purple and red sweet peas.
Royal Correspondent Tim Ewart reports on Jubilee preparations.
And stars like Stevie Wonder, Sir Paul McCartney and Sir Elton John will perform at a concert the following day in honour of the longest reigning monarch since Queen Victoria.
A special visual tribute will see Diamond Jubilee Beacons light up the night sky across the UK on Monday, with more than 4,000 expected to be lit here and in the Commonwealth.
ITV News reporter Richard Pallot reports on how the nation is preparing for the weekend of celebrations.
A St Paul's Cathedral service of thanksgiving will be the highlight of Tuesday, ending with the Queen appearing on Buckingham Palace's balcony to acknowledge the tens of thousands expected to fill The Mall.
Prime Minister David Cameron, the Duke of Edinburgh, Prince of Wales and other senior royals will join prominent individuals from the UK and abroad at many of the events.
– David Cameron speaking to Parliament's The House magazine
I owe the Queen a huge debt for the wisdom she has shown me over the past couple of years.
Six decades of service have given her an acute sense of what matters, what is permanent, and what is in Britain's best interests.
As her previous prime ministers have found, those insights are extremely useful. She is quite simply a remarkable person and a towering figure in our history. Long may she reign.
Downing Street is already draped in bunting ahead of the celebrations that could see six million Brits throw a Jubilee party this weekend.
The Queen will join Charles, Camilla, the Duke and Duchess of Cambridge and Prince Harry on the Royal Barge for the River Pageant on the Thames this Sunday.
In the shadow of Buckingham Palace, the concert in honour of the Queen will see Stevie Wonder joined by other names like Dame Shirley Bassey, Cheryl Cole, Grace Jones, Sir Tom Jones, Annie Lennox, will.i.am and Robbie Williams.
The Queen will be invited on to the stage on Monday night to light the national, and last, Jubilee Beacon by dropping a diamond-shaped crystal into a pod.
During the final day of celebrations, the Archbishop of Canterbury, Dr Rowan Williams, is expected to pay tribute to the monarch in his sermon at the St Paul's Cathedral service of thanksgiving.
Conditions on Saturday are expected to be cooler than recent days and there may be a spot of drizzle.
Sunday's river pageant on the Thames could be accompanied by showers and cold conditions.
Monday could be drier and brighter for the concert, and the following day could see another weather front arriving from the west, bringing more rain.