A rapturous flag-waving crowd of more than 100,000 cheered Queen Elizabeth II at Epsom racecourse in Britain on Saturday as she arrived to kick off four days of celebrations for her diamond jubilee.

Shortly after gun salutes across the country marked the exact anniversary of her coronation, the horse-loving 86-year-old monarch was driven across the racecourse in an open-topped vehicle, dressed in royal blue.

Paratroopers descended to the racecourse trailing huge Union Jack flags and red smoke ahead of the the arrival of the queen and her 90-year-old husband Prince Philip to watch the Epsom Derby, Britain's richest horse race.

In a surge of enthusiasm for the monarchy across Britain, thousands of people meanwhile paraded through the Scottish city of Perth for the jubilee, and many more held community parties.

"It's not every morning you wake up on a day that will be written about in the history books," declared the Sun, Britain's best-selling newspaper.

"Make the most of this once-in-a-lifetime occasion. It may be centuries before another comes along."

Crowds even turned out to watch military bands rehearse in London ahead of the main celebrations for the queen's 60 years on the throne.

Cloudy weather and forecasts of rain appeared unlikely to deter the public from partying amid the highest support for the royals in decades. A recent poll showed about 80 percent of Britons want the country to stay a monarchy.

People were already camping in tents beside the Thames river ahead of a pageant of about 1,000 boats that will sail through London on Sunday with the 86-year-old queen in a royal barge decked with 10,000 flowers.

"There is huge excitement. The queen has done a terrific job in the past 60 years," said Andrew Phasey, whose canal narrowboat will be part of the pageant.

"We feel hugely privileged to be taking part. It will be a terrific day."

Britons have planned more than 9,500 street parties for Sunday, although there are concerns about forecasts of heavy rain.

On Monday, some 4,000 beacons will be lit across the Commonwealth following a huge picnic and star-studded concert at Buckingham Palace.

Tuesday -- like Monday a public holiday -- is devoted to ceremonial events including a thanksgiving service and carriage procession.

At the racecourse on Saturday, popular mezzo-soprano Katherine Jenkins sang the national anthem as the queen arrived along with her sons Andrew and Edward, young princesses Beatrice and Eugenie, and other members of the royal family.

Prince Philip waved his top hat at the crowds as the queen smiled broadly.

But Prince William and wife Catherine -- whose wedding last year drew two billion TV viewers and was credited with reviving public interest in the royals -- were absent.

Queen Elizabeth, a keen rider and racehorse owner, was to present the 110-year-old Coronation Cup, renamed the Diamond Jubilee Coronation Cup, to the winner of one of the six other races taking place Saturday at Epsom, southwest of London, besides the Derby.

Rachel Molloy, 28, a singer from London, said over strawberries and champagne, "We waved to her and it was very exciting because we've never seen the queen this close. She looked happy."

Thousands of people including 1,000 pipers and drummers were meanwhile parading through Perth despite an ongoing campaign north of the border for independence from the United Kingdom.

In Northern Ireland, even republican party Sinn Fein has supported celebrations and offered a gift to the queen for the occasion.

Shops across Britain were doing a brisk trade in Union Jack accessories, bunting, commemorative china and masks of the royals.

Festivities are set to be more muted across the Commonwealth, mostly made up of former British colonies, but British soldiers were pictured in Afghanistan serving celebratory tea from a gold-coloured teapot.

The queen acceded to the throne on February 6, 1952, upon the death of her father King George VI while she was away in Kenya, and was crowned the following year on June 2, amid massive public enthusiasm despite heavy rain.