Britain's Queen Elizabeth II began a four-day series of celebrations to mark the 60th anniversary of her becoming queen with a visit to the horse races close to her Windsor home on Saturday afternoon.

Queen Elizabeth arrived at the Epsom racecourse in south London as onlookers and racegoers cheered and waved flags.

Ceremonial gun salutes were fired to mark the Jubilee weekend in central London by the King's Troop, Royal Horse Artillery at Horse Guards Parade and by the Honourable Artillery Company at the Tower of London.

Further ceremonial gun salutes were fired at Edinburgh Castle and in the Welsh capital of Cardiff and the Northern Ireland capital of Belfast.

Queen Elizabeth has a passionate interest in horse-racing and horse-breeding, and regularly attends the annual races at Epsom racecourse, one of the highlights of the British flat-racing season.

The day's seven races included the famous Epsom Derby. Queen Elizabeth has owned horses which have entered the Derby on 10 occasions, the first in 1953, but she has failed to win the race and it remains the only one of the top five flat races that she has failed to win.

The coming three days will see a series of events planned in celebration of the Diamond Jubilee.

On Sunday, a flotilla of 1,000 boats will accompany the Queen on a royal barge as it sails down the Thames through central London. Police estimate crowds of up to 1 million will watch from the river banks.

Also on Sunday, thousands of street parties and street lunches will be held across the country.

On Monday, a musical concert will be held at Buckingham Palace for the public and a chain of beacon fires will be lit in celebration in the evening.

The Diamond Jubilee weekend concludes on Tuesday with the Queen making a ceremonial procession through London to St Paul's Cathedral where a thanksgiving service will be held.

Queen Elizabeth is only the second British or English monarch in over 1000 years to celebrate a Diamond Jubilee, Queen Victoria being the first in 1897.