Derby Day spectators welcomed the Queen as she began her Diamond Jubilee celebrations on Saturday.
Racegoers cheered and applauded her on her annual visit to the event at Epsom.
She chose to spend the start of national festivities marking her 60-year reign in a world she knows well - one of thoroughbreds, jockeys, trainers and owners.
Leaden skies which threatened rain gave way to summer sunshine after the Queen took her place in the Royal Box, surrounded by her family and with horse trainer John Warren on hand for some valuable advice.
Epsom racegoers celebrate the Jubilee on an open top bus ahead of the Queen's outing to the Derby
The four-day bank holiday will see spectacular events staged across the nation, and the Archbishop of York joined the growing ranks paying tribute to the Queen this weekend.
Dr John Sentamu, who was five days away from his third birthday at the time of the Queen's 1953 Coronation, said: "The thing about the Queen is she's just an ordinary English person with a great sense of humour.
"If you're not very careful, she could pull your leg without you realising she's pulling your leg. She has no airs and graces."
A cheer went up when the Queen and Duke of Edinburgh were driven down the Surrey racecourse and, when they stepped from their state limousine, soprano Katherine Jenkins was on hand to sing the National Anthem.
The Welsh star, who has recently been competing in Dancing With The Stars in the US, said: "I've met the Queen before. I've been to lunch at Buckingham Palace, but it was a huge honour to be part of this and kick-start the whole celebrations around the country."
Ashleigh Butler and her dog Pudsey, winners of this year's Britain's Got Talent, also entertained the crowds with their tricks.
The Queen and Duke were joined by a large party which included the Duke of York and his daughters, Princesses Beatrice and Eugenie.
The Earl and Countess and Wessex were also in the Royal Box along with the Duke and Duchess of Gloucester, and Prince and Princess Michael of Kent.
The royal women wore summer dresses, while the men had donned morning suits and carried top hats.
Derby Day is an occasion when all elements of British society gather on the Epsom Downs.
The wealthy, wearing top hats and tails, sipped champagne in the Queen's Stand, and on the course's famous hill in the middle of the track a funfair and amusements were staged for other racegoers.
Welsh singer Katherine Jenkins sang the national anthem as the Band of Her Majesty's Royal Marines Portsmouth played and when it ended, a huge cheer went up.
Thoroughbreds owned by the Queen have won four out of the five flat racing classics: the 1,000 Guineas and 2,000 Guineas, the Oaks and the St Leger, with only the Derby eluding her.
The Queen has had 10 runners in the Derby - the first in 1953 and the latest in 2011, when Carlton House finished third.
The closest she has come to winning the race (in terms of placing) was in 1953 - the year of her Coronation - when Aureole finished second to Pinza.
The Queen made her first appearance in the parade ring to watch the horses in the Diamond Jubilee Coronation Cup - renamed in her honour.
Carrying a Derby Day programme, she stood beside the Duke, who wore a morning suit and top hat and carried a umbrella.
As the thoroughbreds were paraded around the ring, the Queen watched them intently, and carried on scrutinising them as their jockeys climbed into their saddles.
The race was won easily by St Nicholas Abbey and the Queen presented trophies to the winning owners, trainer and jockey. Philip and Edward watched from the Royal Box and shared a joke as they looked down on the presentation.
The excitement built ahead of the Derby and the Queen was joined by her family in the parade ring as she got a closer look at the thoroughbreds due to race.
When the Derby finally got under way, a great cheer went up and the bars, cafes and restaurants in the stands emptied as spectators flocked to the rails.
The Queen was not on the balcony with the rest of the royal party to watch as the favourite, Camelot, cruised from near the back of the field to a comfortable win.
But when it was paraded in the winner's circle, she came out into the bright sunshine to watch the jockey dismount and be congratulated by the owners and trainer Mr O'Brien, whose horse had earlier won the Diamond Jubilee Coronation Cup.
During the day a horse part-owned through a syndicate by the parents of the Duchess of Cambridge, Michael and Carole Middleton, ran in a race.
Sohraab, owned by Pangfield Racing, was entered in the Investec Specialist Bank "Dash" but finished well down the field.
The extended Bank Holiday weekend will also feature a majestic River Thames pageant on Sunday. The following day pop music legends will entertain the royals and Jubilee beacons will light up hilltops across the country.
On Friday prime minister David Cameron hailed the Queen saying she had never "put a foot wrong."
"She's hugely popular and respected here and around the world; it's an opportunity to give thanks and say thank you for the incredible service she has given."