Buckingham Palace yesterday showed off rarely-seen royal treasures illustrating a year in the life of Queen Elizabeth II when her official residence opened its doors to the public yesterday.

The royal palace is highlighting the 84-year-old monarch's annual duties in its exhibition The Queen's Year, open during the two months when the sovereign is away.

"It's really designed to provide an insight into the Queen's life, all the things Her Majesty is involved in during the course of the year," co-curator David Oakey said.

"We always try and present an aspect of the Queen. People will be aware that the Queen works really hard, but they might not know how."

Split into seasons, the exhibition in the opulent state rooms - normally used for investitures and receiving dignitaries - focuses on yearly events such as the summer garden parties, the Queen's birthday parade, Ascot races, Remembrance Sunday and her Christmas message.

The chief item on display is Queen Elizabeth's 5.5-metre long Robe of State, worn to the state opening of Parliament, which has never been exhibited before.

It is presented alongside the Great Sword of State, and the sword used by the Queen to confer knighthoods.

The 19 state rooms have been opened to the public in August and September since 1993, when the palace is not being used in its official capacity and the Queen is on holiday or at her Balmoral private summer residence in eastern Scotland.

An estimated 400,000 people are expected to visit the palace this year during the two months when the state rooms are open.

"The objective is to show the breadth of the Queen's year," remarked Mr Oakey.

"The theme of the exhibition is interaction between the public and the Queen. The British monarchy has always been very visible.

"A lot of the objects you can see the Queen using at events, so at the state opening you might see the robe, but that's not the same as seeing it in this context.

The exhibition features dresses, hats worn at Ascot, a tiara and even the saddle the Queen used until 1986 at Trooping The Colour, her annual birthday parade.

It also includes gifts given to the Queen on visits, including a statue of cartoon characters Wallace and Gromit, a signed cricket bat, and a fake "Buckingham Palace" London Underground station sign.

The state rooms include paintings by Rembrandt, Rubens, Titian, Van Dyck, Poussin and Canaletto.

A new cafe has been installed on the West Terrace this year, allowing visitors to take tea while looking out over the Buckinghham Palace gardens.