LONDON (REUTERS) - A beaming Queen Elizabeth waved to cheering crowds massed outside Buckingham Palace on Thursday (June 2) as Britain kicked off four days of pomp, parties and parades to celebrate her record-breaking 70 years on the British throne.

Tens of thousands of royal supporters waving flags lined the streets of London for a military parade that marked the start of Platinum Jubilee events.

Millions of people across Britain and the world were expected to join street parties, watch the festivities and light beacons in honour of the 96-year-old queen.

Queen Elizabeth, holding a walking stick and wearing a dusky dove blue outfit that she also wore for an official Jubilee photograph released on Thursday, was joined by her son and heir Prince Charles, 73, and other senior royals on the balcony of Buckingham Palace.

Queen Elizabeth has been on the throne for longer than any of her predecessors, and is the third-longest reigning monarch ever of a sovereign state.

"Thank you to everyone who has been involved in convening communities, families, neighbours and friends to mark my Platinum Jubilee, in the United Kingdom and across the Commonwealth," she said in a statement as the festivities got under way.

"I continue to be inspired by the goodwill shown to me, and hope that the coming days will provide an opportunity to reflect on all that has been achieved during the last 70 years, as we look to the future with confidence and enthusiasm."

The crowds cheered as the royals watched a fly-past by modern and historic Royal Air Force planes. The queen’s great-grandchildren waved at the planes as they roared past overhead.

Thursday marks not only the start of the Jubilee, but also the 69th anniversary of the coronation of Queen Elizabeth, who became queen on the death of her father George VI in February 1952.

In a sign of the monarch’s age and recent “episodic mobility” issues that have led her to cancel some engagements, Queen Elizabeth’s personal involvement in the events will be somewhat limited compared with previous major gatherings.

Military parade

The celebrations began with the Trooping the Colour, a military parade in central London held annually to mark the queen’s official birthday, where 1,500 soldiers marched to military music in ceremonial uniforms of scarlet tunics and bearskin hats.

A number of people caused a brief disturbance by running out in front of marching soldiers on the Mall boulevard before they were dragged away by police. Several were arrested.

Senior royals, including Prince Charles, 73, and his eldest son William, 39, are carrying out some ceremonial duties on the queen’s behalf, although much attention will be focused on those who will not be present.

The queen's second son Prince Andrew, 62, who settled a US lawsuit in February in which he was accused of sexually abusing a woman when she was underage, is not expected to attend. Prince Andrew denied the accusation.

Her grandson Prince Harry, now living in Los Angeles with his American wife Meghan after stepping down from royal duties, watched the parade but was absent from the palace balcony to watch the fly-past, with only “working” members of the family present.

There were artillery gun salutes in London, across Britain and from Royal Navy ships at sea. In the evening beacons will be lit across the country and the Commonwealth, with the queen leading the lighting of the Principal Platinum Jubilee Beacon at her Windsor Castle home.

French President Emmanuel Macron, Pope Francis and former British prime ministers were among those sending messages of goodwill.

Opinion polls show she remains hugely popular and respected among British people, with one survey this week showing eight in 10 people held a positive view of her, and another found three-quarters thought she had done a good job as queen.

"I cannot think of any other public figure, any other celebrity, any other president ... who could possibly have remained so popular," former Prime Minister John Major told BBC radio.

"Her life has been played out in public - the highs, the lows, the good bits and not so good bits. The queen has represented our better selves for over 70 years," said Mr Major, one of 14 leaders to have served under Queen Elizabeth.

Not everyone will be joining in the festivities though.

Anti-monarchy campaign group Republic, which is putting up the message "Make Elizabeth the last" on billboards across Britain, said another poll showed more than half of the public were not interested in the jubilee.