A bronze bust cast to mark the association's 100th anniversary, celebrated last year, was unveiled as she visited the organisation's headquarters in central London.

The Queen toured Baden-Powell House in Kensington, a building she last visited in 1961 when she opened the facility.

Before the unveiling the association's chief scout, Peter Duncan, the former Blue Peter presenter, told an audience of dignitaries and young scouts: "In 1906 Robert Baden-Powell wrote one of the most popular books of the 20th century – Scouting For Boys.

"Radical for its time it contained such views as social responsibility, citizenship and contained a wealth of ideas on how to experience the outdoors whatever your background.

"One hundred years on these are still the issues that surround young people today and make the scouting movement even more relevant."

The Queen then unveiled the bust of herself created by artist Frances Segelman, who has made sculptures of celebrities, sports people and royalty including the Duke of Edinburgh, Elaine Page and Linford Christie.

The polished bronze bust shows the head and shoulders of the Queen, who is wearing a tiara and a diamond necklace.

Ms Segelman described how she had three one hour sittings with the Queen last year and also took pictures to work from.

She added: "The sittings were very, very nerve-wracking, I was measuring the Queen's head with my callipers but she was amazing, she let me carry on measuring and didn't move.

"Throughout all the sittings she was brilliant and sat perfectly still."

During the Queen's visit to Baden-Powell House she was shown young scouts involved in a number of activities from indoor rock climbing to making a campsite and performing circus tricks on stilts.

She has a long association with the movement which held its first camp in August 1907.

Famous former members of the organisation include Sir Paul McCartney, Billy Connolly, Steven Spielberg, David Beckham and the Duke of York, who was a cub scout.

The association, which has the Queen as its patron, celebrated its centenary in 2007 and today has 28 million members around the world.